Always 80 lbs psi in 'E' tires, or go by GVWR?

[Audionut]

On our newly purchased used 2015 KEYSTONE COUGAR 30RLI with ST225/75R15D china bomb original tires on 15x6 wheels, we run them at max recommended 65 lbs psi.

It is overdue for new tires and I’m thinking of going up to a E rated tire due to it is a 36’ TT, 2 axle, dry wt is 7720, and GVWR is 9500lbs.

So when you go up from a D tire with max 65 lbs psi, to an E tire with max 80 lbs psi I was thinking you should run them at the recommended max of 80lbs, however I just spoke with a tire dealer who said to not necessarily run 80lbs. It depends on your GVWR. So do you all agree with that or would you just run 80lbs in them?

And one thing I need to do is weigh my rig to see what our total weight is when it is loaded, but I find it hard to imagine we could be over the GVWR loading it up with just normal living stuff.

[flybouy]

You can go by the load chart. I run 80 psi on my Carlisles.

[Audionut]

You can go by the load chart. I run 80 psi on my Carlisles.


If by the 'load chart' you are talking about the sticker on the left front of the camper, it lists the specs for the ST225/75R15D tires that it came with from the factory, and those of course have a max 65 lbs psi.

And the 'E' tires have max 80 lbs psi that I am thinking of replacing the stock 'D' tires with.

Or are you talking about something else?

What is your GVWR?

[flybouy]

There are manufactures pressure/load charts available on the internet. I think tire rack.com has it as well. We have some regulars on here that are tire experts who most likely will chime in with details.

[sourdough]

With a gvw of 9500 I would be upgrading to LRE. Make sure the wheel will support the new load range (should be stamped on the back). I upgraded to the LRE and run 80psi; much stouter tire and better ride.

[GMcKenzie]

If you run at 80 psi, and it is "too much" the center of the tire may wear out before the edges. But you'll still replace them long before the center runs out of tread (unless you tow a lot), so when I did this (May) I just filled them to 80 and have less rolling resistance.

By all rights you should do the chalk test (chalk line across the tire tread, roll forward and see if the line comes off evenly) but I think airing them up won't do any harm.

[Audionut]

If you run at 80 psi, and it is "too much" the center of the tire may wear out before the edges. But you'll still replace them long before the center runs out of tread (unless you tow a lot), so when I did this (May) I just filled them to 80 and have less rolling resistance.

By all rights you should do the chalk test (chalk line across the tire tread, roll forward and see if the line comes off evenly) but I think airing them up won't do any harm.



With our 2015 Keystone 36’ TT, 2 axle, dry wt 7720 lbs, and GVWR 9500 lbs, came from the factory with ST225/75R15D, from what I've been told I should go up to storage, crawl under and look at the back of the wheels and see what the wheels PSI is rated for. It may be only rated for 65 psi? So I may have to replace the wheels if I go up to a E load tire with a max psi of 80?

We bought used, but I am pretty sure they are the stock wheels Keystone put on, and they look like 6 lug aluminum spoke type wheels and hope I don't have to switch out the wheels.


Now I just read this Q&A on etrailer.com:

https://www.etrailer.com/question-60785.html


Question:
I wanted to know if I can go from the 225/75R15D tire that I currently have on my trailer, to a 225/75R15E tire? Will my current wheel, be able to handle the increased tire pressure needed for the E load range rated tire? Ive been reading about wheel ratings for tire pressure, and Im not sure what my current wheel is rated for. I was just curious, if I were to have E load rating tires installed, if I would need to have different wheels to match the tire pressure rating for the new E load tires. The tire person I spoke with, said I could just run the same tire pressure of 65 psi as with the D load rating tires I have on there currently. The reason why Im asking is, they have the E load rating tires in stock and my load on the trailer hasnt changed. They said the E load rating would just be a higher load rating if nothing more, especially when running the tire pressure at 65 psi. It would just handle the same load as my D load rated tire I have on. Is this correct? Just curious to know, so Im not doing something thats wrong.

Expert Reply:
Different size and bolt pattern wheels that take the same tire size will have different psi ratings. If your existing wheels are rated for 65 psi then it is less likely that they would also be rated for 80 psi which is what an ST225/75-15 load range E tire requires.

Trailer tires should always be inflated to the maximum psi as indicated on the tire. The person you spoke with must not have known about the difference between trailer tires and passenger vehicle tires. Trailer tires are made with a thicker sidewall and if they are under inflated they would generate excessive heat and cause the tire to fail.

If you wanted to go to load range E I would also replace the wheels. Also keep in mind that going to a higher capacity tire does not increase the capacity of the trailer.

[sourdough]

If it has 6 lug wheels more than likely they are rated for 80psi/2830lbs. Look at one to be sure.

IF you wanted to go to LRE AND run 80psi and the current wheels are only rated for 65psi/2540lbs., then yes, you would need to replace the wheels to run that pressure. But, let's assume/hope that the existing wheels are rated for the 80psi - won't take but a minute to look.:)

[Audionut]

Not sure if someone could recognize if this wheel is rated for 80 lbs psi or not by its picture. But the camper is a few miles away in storage and can't go see it until next week.

[Audionut]

Also, what is the difference between an 'E' rated tire and LRE?

[Audionut]

And this is the load rating sticker on our camper.

[flybouy]

Not sure if someone could recognize if this wheel is rated for 80 lbs psi or not by its picture. But the camper is a few miles away in storage and can't go see it until next week.

They look like Sendel wheels (sendelwheel.com) but I'd still recommend you confirm.

[JRTJH]

The key to what pressure rating/load rating YOUR wheels have is stamped on the back of each wheel. This photo will show you what's cast into the spokes on the wheel. In the photo, the wheel "casting" can be drilled for either 5 lug or 6 lug applications and the load rating depends on which lug holes are drilled into the casting.
5H MAX LOAD 2150
6H MAX LOAD 2830

Some 15" wheels are rated for LRC (6 ply rating) tires, some 15" wheels are rated for LRD (8 ply rating) tires, some 15" wheels are rated for LRE (10 ply rating) tires and some are, depending on the number of lug holes, rated for different tire ratings. It's sort of like playing a trumpet, press 1 or 2 or 3 or none of the valves and get something different out the end.... Wheels are much the same, depending on the manufacturer, style, lugs, casting and even the aluminum alloy used in the casting.

There are a number of "competing wheel brands" many that look "identical on the road side" that are rated differently, some 15" 6 lug wheels may only be rated for 2150 pounds while some 15" 5 lug wheels may be rated 2540 pounds. It depends on what brand and what rating is cast on YOUR wheels. Making a "best guess" that you "might have" something that looks like mine but is a different manufacturer's wheel... Well, that gets you to the *** U ME factor. I'd urge you to check the back of your wheels and not guess on what "might be".....

[Canonman]

I found these on RecStuff.com. They look a lot like the ones pictured in your post. Made by Hi Spec. The interesting part is the recommended PSI is based on the valve stem. Anywhere from 60 to 130 PSI.
https://recstuff.com/trailer-tires-wheels/trailer-wheels/15-trailer-rims/15x6-6-lug-on-5-5-aluminum-s5-trailer-wheel-black-s556655b/
When I had my Carlisle LRE's mounted (original tires were LRD) I had them install new metal valve stems to ensure 80 PSI compatability and also because they were recommended for mounting the TPMS transmitters I use.
Bottom line, I'd check with the tire professionals where you are buying your replacement tires.

[Audionut]

The key to what pressure rating/load rating YOUR wheels have is stamped on the back of each wheel. This photo will show you what's cast into the spokes on the wheel. In the photo, the wheel "casting" can be drilled for either 5 lug or 6 lug applications and the load rating depends on which lug holes are drilled into the casting.
5H MAX LOAD 2150
6H MAX LOAD 2830

Some 15" wheels are rated for LRC (6 ply rating) tires, some 15" wheels are rated for LRD (8 ply rating) tires, some 15" wheels are rated for LRE (10 ply rating) tires and some are, depending on the number of lug holes, rated for different tire ratings. It's sort of like playing a trumpet, press 1 or 2 or 3 or none of the valves and get something different out the end.... Wheels are much the same, depending on the manufacturer, style, lugs, casting and even the aluminum alloy used in the casting.

There are a number of "competing wheel brands" many that look "identical on the road side" that are rated differently, some 15" 6 lug wheels may only be rated for 2150 pounds while some 15" 5 lug wheels may be rated 2540 pounds. It depends on what brand and what rating is cast on YOUR wheels. Making a "best guess" that you "might have" something that looks like mine but is a different manufacturer's wheel... Well, that gets you to the *** U ME factor. I'd urge you to check the back of your wheels and not guess on what "might be".....


Thank you for the good info. I think I have decided to go with the Carlisle Trail HD Trailer Radial, it seems to get mostly good reviews. So I will just need to take the trip up to storage and crawl underneath to see what ratings they have.

[Audionut]

I found these on RecStuff.com. They look a lot like the ones pictured in your post. Made by Hi Spec. The interesting part is the recommended PSI is based on the valve stem. Anywhere from 60 to 130 PSI.
https://recstuff.com/trailer-tires-wheels/trailer-wheels/15-trailer-rims/15x6-6-lug-on-5-5-aluminum-s5-trailer-wheel-black-s556655b/
When I had my Carlisle LRE's mounted (original tires were LRD) I had them install new metal valve stems to ensure 80 PSI compatability and also because they were recommended for mounting the TPMS transmitters I use.
Bottom line, I'd check with the tire professionals where you are buying your replacement tires.



I had planned to have metal stems installed because of just that reason for the TPMS I will install. But I didn't know about the PSI compatibility requirement. Thanks for that.

[JRTJH]

Thank you for the good info. I think I have decided to go with the Carlisle Trail HD Trailer Radial, it seems to get mostly good reviews. So I will just need to take the trip up to storage and crawl underneath to see what ratings they have.

I've been running Carlisle Radial Trail tires for the past 8 years. The previous ones in 2011 and 2015 were Radial Trail RH and the last set is Radial Trail HD. The RH was replaced by the HD in 2016. I've had excellent results with the Carlisle Radial Trail tires and once you get a chance to compare them "side by side" to the TowMax, I think you'll easily see why they give better service and reliability.

As for metal valve stems, don't expect your tire store to have metal stems that will fit the trailer wheels. Typically they have metal stems that will fit a steel wheel, but the greater thickness of aluminum wheels means those stems are too short and won't fit. If you want metal valve stems, check with the installer and see if they have stems that fit your wheels, otherwise, order them from a Ford dealer or locate them online and have them on hand for the installer. If not, chances are you'll wind up with rubber valve stems as they're the only ones that won't leak. BTDT

[Audionut]

I've been running Carlisle Radial Trail tires for the past 8 years. The previous ones in 2011 and 2015 were Radial Trail RH and the last set is Radial Trail HD. The RH was replaced by the HD in 2016. I've had excellent results with the Carlisle Radial Trail tires and once you get a chance to compare them "side by side" to the TowMax, I think you'll easily see why they give better service and reliability.

As for metal valve stems, don't expect your tire store to have metal stems that will fit the trailer wheels. Typically they have metal stems that will fit a steel wheel, but the greater thickness of aluminum wheels means those stems are too short and won't fit. If you want metal valve stems, check with the installer and see if they have stems that fit your wheels, otherwise, order them from a Ford dealer or locate them online and have them on hand for the installer. If not, chances are you'll wind up with rubber valve stems as they're the only ones that won't leak. BTDT


Thanks for the heads-up on that! Good to know.

So, did you have any recommendations on a brand of metal stem that may fit and one that didn't leak?

[Canonman]

Thanks for the heads-up on that! Good to know.

So, did you have any recommendations on a brand of metal stem that may fit and one that didn't leak?

Don't know if you have a Les Schwab store (they're all over the west) but they never made any issue of it to me. Charged a few $ more but not a lot.

[JRTJH]

The ones I used and that others on the forum have used are HalTec N-1600 Ford F Series Truck Valve. They're available at almost any internet tire/wheel site and usually are about $4 each. Shipping is almost as much as the valves, so expect to pay about $25 or so for 4 delivered to your house.

Here's one link, cheap price for the valve stems but a killer on the shipping...
https://yourtireshopsupply.com/product/512/n1600-ford-series-truck-valve-han1600

[Audionut]

The ones I used and that others on the forum have used are HalTec N-1600 Ford F Series Truck Valve. They're available at almost any internet tire/wheel site and usually are about $4 each. Shipping is almost as much as the valves, so expect to pay about $25 or so for 4 delivered to your house.

Here's one link, cheap price for the valve stems but a killer on the shipping...
https://yourtireshopsupply.com/product/512/n1600-ford-series-truck-valve-han1600



Is this one of the good metal valve stems that doesn't leak or are they all susceptible to that?

And is that one that is long enough to fit aluminum wheels like we have?

TIA

[tech740]

Is this one of the good metal valve stems that doesn't leak or are they all susceptible to that?

And is that one that is long enough to fit aluminum wheels like we have?

TIA

Those ones work great. My old cougar had wheels that looked like yours. They went right in and I didn't have any issues in the few years I had it before trading the camper.

[Roscommon48]

they are rated for 80psi, run them at that or very near that. I assume the wheels will been able to accept these tires.


good safety margin

[Gegrad]

I ordered my Radial Trail HDs from WalMart.com and had them shipped to the store. I had just purchased new wheels to handle the LRE tires, so I took the wheels and had the tires mounted. Wal Mart had metal valve stems on hand that fit and everything has been rosy for just over 2 years now. I have lost a total of maybe 10 psi over the 2 years I have had them, including 2 winters.

[busterbrown]

The ones I used and that others on the forum have used are HalTec N-1600 Ford F Series Truck Valve. They're available at almost any internet tire/wheel site and usually are about $4 each. Shipping is almost as much as the valves, so expect to pay about $25 or so for 4 delivered to your house.

Here's one link, cheap price for the valve stems but a killer on the shipping...
https://yourtireshopsupply.com/product/512/n1600-ford-series-truck-valve-han1600

I've used the same stems on two sets of ST tires on my coach. NO issues; no air loss. Would use these again and again.

[busterbrown]

I ordered my Radial Trail HDs from WalMart.com and had them shipped to the store. I had just purchased new wheels to handle the LRE tires, so I took the wheels and had the tires mounted. Wal Mart had metal valve stems on hand that fit and everything has been rosy for just over 2 years now. I have lost a total of maybe 10 psi over the 2 years I have had them, including 2 winters.

Did the exact same thing but used N-1600 Fseries stems instead. The wheels I purchased off Recstuff.com. Walmart had the best pricing on the tires.

[JRTJH]

When I bought new trailer tires in August, WalMart had the best pricing on 225 75R15 LRE Carlisle Radial Trail HD tires that I could find. Plus, their mount/balance ($15) was/is cheaper than anywhere around here. Our store didn't have the steel valve stems to fit the Sendell wheels, but I reused the ones that were already installed, so I really didn't need new valve stems.

[flybouy]

When I bought new trailer tires in August, WalMart had the best pricing on 225 75R15 LRE Carlisle Radial Trail HD tires that I could find. Plus, their mount/balance ($15) was/is cheaper than anywhere around here. Our store didn't have the steel valve stems to fit the Sendell wheels, but I reused the ones that were already installed, so I really didn't need new valve stems.

Was WalMart able to lug centric balance ?

[busterbrown]

Was WalMart able to lug centric balance ?

Most chain retailers don't have the equipment (plate or wheel balancer adapters) for lug centric balancing. I checked about 10 different places near me and only found 1 that had the equipment. As far as I know, most will not.

[flybouy]

Most chain retailers don't have the equipment (plate or wheel balancer adapters) for lug centric balancing. I checked about 10 different places near me and only found 1 that had the equipment. As far as I know, most will not.

Thanks, I'm well aware of the rarity in finding lug centric balancing. By quoting John's post I was asking John this question. John had it done a few weeks ago so I'm curious if they now offer it or was he just lumping services together as that's how most places list the service.

[CWtheMan]

On our newly purchased used 2015 KEYSTONE COUGAR 30RLI with ST225/75R15D china bomb original tires on 15x6 wheels, we run them at max recommended 65 lbs psi.

It is overdue for new tires and I’m thinking of going up to a E rated tire due to it is a 36’ TT, 2 axle, dry wt is 7720, and GVWR is 9500lbs.

So when you go up from a D tire with max 65 lbs psi, to an E tire with max 80 lbs psi I was thinking you should run them at the recommended max of 80lbs, however I just spoke with a tire dealer who said to not necessarily run 80lbs. It depends on your GVWR. So do you all agree with that or would you just run 80lbs in them?

And one thing I need to do is weigh my rig to see what our total weight is when it is loaded, but I find it hard to imagine we could be over the GVWR loading it up with just normal living stuff.

I'm a little late entering this post so I'm just going to say; what I post is the way it's supposed to be addressed.

According to your certification label, your OE tires are ST225/75R15D, the "D" represents Load Range D or LRD. When you use a replacement sized ST225/75R15E you have changed nothing except the maximum load capacity. However, there are safety precautions you should insure are in place. The valve stems must be pressure rated for the 80 PSI necessary to gain full advantage of the extra load capacity (steel ones are recommended). The wheels must have the capability to support 80 PSI inflation pressures.

Regardless of what others might say, your OE tires were installed under the guidance of FMVSS. Those standards & the USTMA support the vehicle certified recommended cold inflation pressures to be the very minimum requirement. Therefore, the replacements fully meet that requirement depicted on the certification label, because the LRD & LRE both provide identical load capacities at 65 PSI. To gain the advantage of the LRE you have the option to use optional inflation pressures from 66-80 PSI.

The reference is a TRA standardized load inflation chart containing your tire size.

https://fifthwheelst.com/documents/Copy%20of%20Load%20and%20Inflation%20All%20ST-Modified.pdf

[Audionut]

I'm a little late entering this post so I'm just going to say; what I post is the way it's supposed to be addressed.

According to your certification label, your OE tires are ST225/75R15D, the "D" represents Load Range D or LRD. When you use a replacement sized ST225/75R15E you have changed nothing except the maximum load capacity. However, there are safety precautions you should insure are in place. The valve stems must be pressure rated for the 80 PSI necessary to gain full advantage of the extra load capacity (steel ones are recommended). The wheels must have the capability to support 80 PSI inflation pressures.

Regardless of what others might say, your OE tires were installed under the guidance of FMVSS. Those standards & the USTMA support the vehicle certified recommended cold inflation pressures to be the very minimum requirement. Therefore, the replacements fully meet that requirement depicted on the certification label, because the LRD & LRE both provide identical load capacities at 65 PSI. To gain the advantage of the LRE you have the option to use optional inflation pressures from 66-80 PSI.

The reference is a TRA standardized load inflation chart containing your tire size.

https://fifthwheelst.com/documents/Copy%20of%20Load%20and%20Inflation%20All%20ST-Modified.pdf


Not that you would want to, but it appears the LRE tires could be run at 65 psi without any damage to the tire? However, it's load capacity would not exceed that of LRD tires if you ran them only at 65 psi.

And you would only get the higher load capacity out of them when at higher psi, (66-80)? And wheel and valve stem must be rated for 80 psi.

I then wonder if it is really recommended to go to a LRE from LRD tire for our 36’ TT, 2 axle, dry wt 7720, and GVWR is 9500 lbs camper?

I would think even if you ran a LRE at 65 psi it would be a more durable tire with it's extra plys than the LRD? And, if so, that may be worth a little more 'peace of mind' knowing it would be less susceptible to blowouts on the road?

[CWtheMan]

Not that you would want to, but it appears the LRE tires could be run at 65 psi without any damage to the tire? However, it's load capacity would not exceed that of LRD tires if you ran them only at 65 psi.

And you would only get the higher load capacity out of them when at higher psi, (66-80)? And wheel and valve stem must be rated for 80 psi.

I then wonder if it is really recommended to go to a LRE from LRD tire for our 36’ TT, 2 axle, dry wt 7720, and GVWR is 9500 lbs camper?

I would think even if you ran a LRE at 65 psi it would be a more durable tire with it's extra plys than the LRD? And, if so, that may be worth a little more 'peace of mind' knowing it would be less susceptible to blowouts on the road?

Durability is a ponderance. Load capacity is a measurement of the load capacity a tire can support at given inflation values.

When replacing RV trailer tires with tires having a higher load capacity the owner is usually looking for more load capacity reserves. Personally, I want at least 15% reserve capacity above the vehicle certified GAWRs.

Hypothetical 4400# vehicle certified axle = 4400 X 1.15 = 5060 / 2 = 2530. On a Tire chart for the ST225/75R15 LRE I would use 70 PSI (2620#) just to insure a little more stiffness in the sidewalls.

[JRTJH]

I suppose everyone has an opinion about tire load ratings and the "appropriate" tire pressure to run.

Here's mine (for what it's worth):

If we consider a 225 75R15 LRD and a 225 75R19 LRE tire, side by side, the sidewalls on the LRE tire are heavier and thicker. (probably the polyester belts more than extra rubber).

When the two tires are inflated to 65 PSI, they both support 2540 lbs (per the load chart). They both have the same amount of sidewall flexing at that air pressure. I question whether the thicker sidewalls of the LRE tire would have the capacity to dissipate heat as rapidly as the LRD (thinner sidewall).

What I suspect (haven't been able to prove it) without extensive "tire engineering research) is that the LRE tire will run hotter at 65 PSI carrying the same load as the LRD tire at the same pressure and load. Increasing the LRE tire to 80 PSI reduces the sidewall flexing and I'd suspect, reduces the tire temperature if it's carrying the same 2540 pound load.

My theory (again, FWIW) is that the LRE tire will have a lower running temperature and likely a longer lifespan before sidewall breakdown if run at 80 PSI because of less sidewall flexing which causes increased tire temperature.

So, since tire lifespan is more related to time since manufacture rather than tread wear, to obtain "maximum load capacity and minimum sidewall flexing" operating a LRE tire at the maximum sidewall pressure will provide the best tire reliability as well as the best longevity while providing the maximum load capacity which results in an increased lifespan before tire compromise and reduced performance.

As I said, "Just another opinion" not based in "tire engineering research" but in "user induced understanding of what I believe"..... YMMV (and probably will)

[Audionut]

Durability is a ponderance. Load capacity is a measurement of the load capacity a tire can support at given inflation values.

When replacing RV trailer tires with tires having a higher load capacity the owner is usually looking for more load capacity reserves. Personally, I want at least 15% reserve capacity above the vehicle certified GAWRs.

Hypothetical 4400# vehicle certified axle = 4400 X 1.15 = 5060 / 2 = 2530. On a Tire chart for the ST225/75R15 LRE I would use 70 PSI (2620#) just to insure a little more stiffness in the sidewalls.


From what I have read, I think getting the LRE instead of the LRD tires would be a good idea and keeping them at 70-80 psi (depending on GVWR) would be the way to go. And like I said above, it should be a more durable tire with it's extra plys than the LRD. And also from what I've read the Carlisle Radial Trail HD should be a good tire to buy?

[JRTJH]

From what I have read, I think getting the LRE instead of the LRD tires would be a good idea and keeping them at 70-80 psi (depending on GVWR) would be the way to go. And like I said above, it should be a more durable tire with it's extra plys than the LRD. And also from what I've read the Carlisle Radial Trail HD should be a good tire to buy?

All modern ST tires are either 2 ply or 3 ply with a "rating" that equals 6, 8 or 10 ply in the old system. The difference in today's tires in LRD and LRE is more the thickness of the polyester cord used to weave the sidewall "ply" rather than the number of "thin polyester cord layers" used in the ancient "add two more ply layers" construction. GONE are the days of buying a 8 ply or a 10 ply tire. In reality you're buying a 2 ply (or in some cases a 3 ply) tire that has the sidewall strength that equals the old ply rating standard.

[Gegrad]

Did the exact same thing but used N-1600 Fseries stems instead. The wheels I purchased off Recstuff.com. Walmart had the best pricing on the tires.

Yep, got my wheels off Recstuff.com as well. And yep, also had the best tire pricing.

[Stircrazy]

If we consider a 225 75R15 LRD and a 225 75R19 LRE tire, side by side, the sidewalls on the LRE tire are heavier and thicker. (probably the polyester belts more than extra rubber).

When the two tires are inflated to 65 PSI, they both support 2540 lbs (per the load chart). They both have the same amount of sidewall flexing at that air pressure. I question whether the thicker sidewalls of the LRE tire would have the capacity to dissipate heat as rapidly as the LRD (thinner sidewall).



If the side wall is thicker, it would make more sense to me that there would be less flexing on that tire which would result in a little less heat. but it is not rely a factor as that would be a small factor compared to the het from plain old rolling resistance. as for heat dissipation I think the fastest method of removing heat would be from the rim its self acting as a big heat sink. an aluminum rim would even dissipate heat faster, so I am not sure if worrying about the thickness of the sidewall preventing heat dissipation is something we should worry about.

I know all things equal I would always take the thicker sidewall as in theory it should last longer and resist blow out longer.

Steve

[JRTJH]

If the side wall is thicker, it would make more sense to me that there would be less flexing on that tire which would result in a little less heat. but it is not rely a factor as that would be a small factor compared to the het from plain old rolling resistance. as for heat dissipation I think the fastest method of removing heat would be from the rim its self acting as a big heat sink. an aluminum rim would even dissipate heat faster, so I am not sure if worrying about the thickness of the sidewall preventing heat dissipation is something we should worry about.

I know all things equal I would always take the thicker sidewall as in theory it should last longer and resist blow out longer.

Steve

Steve,

In "my imagination of how it works", if you install the LRE tire on a wheel, put it on an axle end that's carrying 2000 pounds, the sidewall will flex more with 65 PSI than it will with 80 PSI. That increased flexing (movement) will create more friction within the rubber and cause more heat to be generated at 65 PSI. At least that's the way I understand how tires work.

I completely agree with you, "all things equal, I would always take the thicker sidewall..."

[flybouy]

Steve,

In "my imagination of how it works", if you install the LRE tire on a wheel, put it on an axle end that's carrying 2000 pounds, the sidewall will flex more with 65 PSI than it will with 80 PSI. That increased flexing (movement) will create more friction within the rubber and cause more heat to be generated at 65 PSI. At least that's the way I understand how tires work.

I completely agree with you, "all things equal, I would always take the thicker sidewall..."

John that's how I understand it as well.
I think some people don't understand that the increased sidewall rating is a function of how much air pressure the tire can withstand, with reserves built in of course. I try to explain it this way, take an unmounted tire and stand on the bead. The tire sidewall will collapse, mount it and fill it with the max inflation air pressure then sit on the tire, the sidewall will not deflect. The more air pressure up the max inflation rating the less the sidewall will flex. Now this CAN cause a passenger tire to wear the center of the tread more but we are not talking about a passenger tire.

[Audionut]

The ones I used and that others on the forum have used are HalTec N-1600 Ford F Series Truck Valve. They're available at almost any internet tire/wheel site and usually are about $4 each. Shipping is almost as much as the valves, so expect to pay about $25 or so for 4 delivered to your house.

Here's one link, cheap price for the valve stems but a killer on the shipping...
https://yourtireshopsupply.com/product/512/n1600-ford-series-truck-valve-han1600


Thanks for the recommendation for the N-1600 stems. Hopefully they are the best choice.

I was trying to see if valve stem holes are all the same size. What I have learned is that for any wheel that is rated for 65 psi the hole is 0.453".
Wheels rated for 80 psi holes also 0.453".
Wheels rated for 100 psi holes are 0.625".

So any wheel rated for 65 psi or 80 psi should have a 0.453" hole. Also, there is a need to not torque the stem to tight, the gasket could be damaged.

Have you found this to be true?


EDIT: NVM, I have the answer.

[sourdough]

Since I'm waiting on my truck and have nothing better to do let me throw this out;

My Carlisle LRE tires run cooler at 80psi than my Trailer Kind LRDs did @65 psi. Of course the LRDs had considerable more weight on them as opposed to their max capacity vs the LREs. Stiffer sidewall? Less flexing? Not really apples to apples but just a thought.

I agree with John that running the LRE tire at 65psi vs the full inflation of 80psi should/will cause more flex thus more heat.....at least that was always my understanding. These are not passenger car radials.

[JRTJH]

Thanks for the recommendation for the N-1600 stems. Hopefully they are the best choice.

I was trying to see if valve stem holes are all the same size. What I have learned is that for any wheel that is rated for 65 psi the hole is 0.453".
Wheels rated for 80 psi holes also 0.453".
Wheels rated for 100 psi holes are 0.625".

So any wheel rated for 65 psi or 80 psi should have a 0.453" hole. Also, there is a need to not torque the stem to tight, the gasket could be damaged.

Have you found this to be true?

Your wheels are the same casting for the 5 lug (65PSI) and the 6 lug (80PSI) rating. That means the valve stem hole size is the same for either rating, since the casting is the same.

As for maximum torque on the valve stem to prevent gasket damage, I'll leave that to the "experts at the tire installation facility"

I believe that you're making this a LOT more difficult than it should be.

[Audionut]

Your wheels are the same casting for the 5 lug (65PSI) and the 6 lug (80PSI) rating. That means the valve stem hole size is the same for either rating, since the casting is the same.

As for maximum torque on the valve stem to prevent gasket damage, I'll leave that to the "experts at the tire installation facility"

I believe that you're making this a LOT more difficult than it should be.


Right you are, as is the case with me, I tend to over research things.

On another note, we brought our camper home to do a little work on it and I crawled under to see what it says behind the 6 lug wheels.

It says:
MAX LOAD
2150&6/2830LBS

So just to be sure, these wheels are 80 psi rated?
Any idea what 2150&6 means?


EDIT: NVM, I figured it out.
.

[JRTJH]

Right you are, as is the case with me, I tend to over research things.

On another note, we brought our camper home to do a little work on it and I crawled under to see what it says behind the 6 lug wheels.

It says:
MAX LOAD
2150&6/2830LBS

So just to be sure, these wheels are 80 psi rated?
Any idea what 2150&6 means?

We're going in circles and not getting anywhere. Go back to my post #13 and look at the photo and my explanation. I've already answered this (and every other question) that keeps coming up as a "new, what if"....

Maybe someone else can more effectively explain it to you where my explanation, complete with photos, is inadequate. Otherwise, maybe you could "take a leap of faith" and believe what me and at least 3 others have told you about those valve stems being correct for the application. :facepalm:

[Audionut]

I am not doubting what you are saying. I was mostly wondering what "2150&6" meant. I just found out that I couldn't see all the numbers behind my wheels due to dirt and such. I see now exactly what I need to know.

I've got it figured out now.
Thank you for your help.

[CWtheMan]

Right you are, as is the case with me, I tend to over research things.

On another note, we brought our camper home to do a little work on it and I crawled under to see what it says behind the 6 lug wheels.

It says:
MAX LOAD
2150&6/2830LBS

So just to be sure, these wheels are 80 psi rated?
Any idea what 2150&6 means?

There are no set in stone load/PSI specifications for wheels. They are certified by SAE and their manufacturer must provide individual specs upon demand.

That information you have found in orange above is probably there because the OEM provider requested it be there from the wheel manufacturer. It's probably an "in-house" reference that the wheel is compatible with tires having load capacities from 2150# LRC to 2830# LRE (which would be ST225/75R15). However the only valid answer in this case is to ask the wheel manufacturer.

If wondering about the size I mentioned, a tire load chart gave me the answer.

[bobbecky]

Take a look at the Sizes & Specs chart on this page and see the 15" size wheels. The 5 lug wheels are rated 2160 lbs and the 6 lug wheels are rated 2860 lbs. These are the same wheel, just with a different number of lug holes. That is what is referenced on the back of the wheel, same casting but with 5 or 6 lug holes. https://www.tredittire.com/wheel/altitude/

[CWtheMan]

Take a look at the Sizes & Specs chart on this page and see the 15" size wheels. The 5 lug wheels are rated 2160 lbs and the 6 lug wheels are rated 2860 lbs. These are the same wheel, just with a different number of lug holes. That is what is referenced on the back of the wheel, same casting but with 5 or 6 lug holes. https://www.tredittire.com/wheel/altitude/

I was responding to this information:

It says:
MAX LOAD
2150&6/2830LBS

If that information is actually on the wheel, it's official and supersedes brochure information.

I used a load inflation chart for tires ST225/75R15 because the 2150 above equals a maximum loaded LRC tire for that tire size, as does the 2830 for a LRE.

Load index numbers do not provide the official load capacity for ST or LT tires. They conform to the load range lettering system. However, you'll find load index numbers on the LT & ST tires because sections of that system are official for all tires. Those sections may be a maximum load capacity when the tire is used in a dual configuration (114/110, the 110 is maximum load for dual configuration). The load index system also provides a speed letter after the load index which is official (114/110L, The "L" is the letter for 75 MPH).

Some "off shore" ST manufacturers may depict actual values on the tire sidewalls. It is also official.

http://www.irv2.com/photopost/showfull.php?photo=35494

[JRTJH]

I was responding to this information:

It says:
MAX LOAD
2150&6/2830LBS

If that information is actually on the wheel, it's official and supersedes brochure information.

I used a load inflation chart for tires ST225/75R15 because the 2150 above equals a maximum loaded LRC tire for that tire size, as does the 2830 for a LRE.

Load index numbers do not provide the official load capacity for ST or LT tires. They conform to the load range lettering system. However, you'll find load index numbers on the LT & ST tires because sections of that system are official for all tires. Those sections may be a maximum load capacity when the tire is used in a dual configuration (114/110, the 110 is maximum load for dual configuration). The load index system also provides a speed letter after the load index which is official (114/110L, The "L" is the letter for 75 MPH).

Some "off shore" ST manufacturers may depict actual values on the tire sidewalls. It is also official.

http://www.irv2.com/photopost/showfull.php?photo=35494

Cal,

Take a look at my photo in post #13 of this thread. Not only does that information exist "ON THE WHEEL" but is on every wheel that I've seen. I'd suspect that it's NOT a Keystone requirement since they wouldn't use both 5 lug and 6 lug castings (with different maximum weights) on the same application. So, the information is on the back of every wheel, at least every wheel that I've pulled on trailers from all manufacturers. Granted, I don't have the occasion to work on as many trailers as some, but every trailer, whether it's Jayco, Winnebago, Keystone or Forest River that I've pulled aluminum wheels, there's a weight rating cast into the wheel and on steel wheels, there's a weight rating either stamped onto the back of the wheel hub, or stamped (with a die set) on the inside of the rim, where you'd need to remove the tire to see the stamp.

[JRTJH]

Here are just a few of the hundreds (maybe thousands) of photos of aluminum and steel wheels that are cast or stamped with information related to offset, weight, lug specifications, manufacturer and other info.

These aren't my photos, but pictures I found using Google search.

[CWtheMan]

Cal,

Take a look at my photo in post #13 of this thread. Not only does that information exist "ON THE WHEEL" but is on every wheel that I've seen. I'd suspect that it's NOT a Keystone requirement since they wouldn't use both 5 lug and 6 lug castings (with different maximum weights) on the same application. So, the information is on the back of every wheel, at least every wheel that I've pulled on trailers from all manufacturers. Granted, I don't have the occasion to work on as many trailers as some, but every trailer, whether it's Jayco, Winnebago, Keystone or Forest River that I've pulled aluminum wheels, there's a weight rating cast into the wheel and on steel wheels, there's a weight rating either stamped onto the back of the wheel hub, or stamped (with a die set) on the inside of the rim, where you'd need to remove the tire to see the stamp.

I already knew what your post #13 said before I posted. I answered the question with the information provided by that specific poster.

In the big picture the OEM providers are not consistent. You have to research each one. Some of them provide information that is targeted for inhouse use by the installers. Other's provide actual specs. That's why, when posting about wheels I always try to add that the only way to get factual information is, ask the wheel manufacturer. Have a look at the web pages for TBC, LionsHead and TBC. They are sort of the big three in providing OEM tires and wheels for our RV trailers. Sendel has a site with all of their trailer wheels depicted. Trailer wheels are not all certified with PSI values. When such wheels are used, the maximum load capacity of the wheel will support whatever PSI is needed for it to support that load.

A side note: The cast aluminum wheels that were OEM (Sendel) on our 2003 Everest (vehicle certified 6000# axles) have a maximum load capacity of 3042# at 80 PSI shown on the inner section of the wheels. Sound familiar? that's the load capacity of LT235/85R16 LRE tires that will not fit our 32" axle spacing. After way over 200,000 miles there're still on that trailer and not leaking. In 2004 & 2005 Keystone reconfigured the axles for those taller tires and they became OEM.

[Apalinto]

Hi Sourdough. What brand of tire did you upgrade to? Do you know if Carlisle makes an LRE?

[sourdough]

Hi Sourdough. What brand of tire did you upgrade to? Do you know if Carlisle makes an LRE?

I upgraded to the Carlisle Radial Trail HD ST 225/75R 15 LRE and I've been very happy with them.

[markjamestx]

I am sure that some of you will not agree with this, but I run E tires of the same size on a 8800# max weight 31 footer TT. Changed from D to E. My brother-in-law (a retiree of Cooper Tire & Rubber) plus the tire dealer which I know very well, recommended 65 to 70 PSI always. Get on down the road and you could exceed the tire's max pressure if you inflate to what is on the side of the tire. On a recent 6,000 mile July-August trip to Montana, my TPMS read 75 to 78 PSI running the highway at 65 to 70 MPH. And, it wasn't that hot up there.

[sourdough]

I am sure that some of you will not agree with this, but I run E tires of the same size on a 8800# max weight 31 footer TT. Changed from D to E. My brother-in-law (a retiree of Cooper Tire & Rubber) plus the tire dealer which I know very well, recommended 65 to 70 PSI always. Get on down the road and you could exceed the tire's max pressure if you inflate to what is on the side of the tire. On a recent 6,000 mile July-August trip to Montana, my TPMS read 75 to 78 PSI running the highway at 65 to 70 MPH. And, it wasn't that hot up there.


The tires are built to withstand the inherent temp increase due to driving. Here is a FAQ from Carlisle:

Carlisle ST FAQ

What is the proper tire inflation?

Maintain air pressure at the maximum PSI recommended on the tire sidewall. It's best to check tire pressure with a quality tire gauge when tires are cold and in the shade.
Under inflation is the number one cause of trailer tire failure. An underinflated tire creates abnormal tire flexing and excessive heat causing:
- Ride and handling problems
- Decreased fuel efficiency
- Reduction of tire life
Driving on tires with too much air is also not recommended. Over-inflated tires are more likely to cut, puncture or fail by sudden impact.

[markjamestx]

In response to sourdough's reply to my post, I wonder why manufacturers put MAX TIRE PRESSURE on their tires? I know the definition of MAX, but go ahead and run them down the road at MAX pressure and you will be exceeding the Manufacturer's MAX tire pressure. Makes sense to me.

[jadatis]

Calculated highest pressure without bumping
Gave for 9500 lbs total weight with 10% of that on pin, for the ST 225/75R15 D-load 73 psi , not allowed, but shows upgrade to E- load is advisable.
For the E-load AT 80 psi , advice 79 psi, so allowed.

For this I lower the loadindex by 6 steps , to give tire same deflection as LT tire would have.
Also the endurance is calculated in maxload for 65mph, though they give max 87mph ( N- speedrated)

Now this is my general system.

Now there are LT225/70R15 tires with loadindex 112S, so max speed 180kmph/112mph, but calculated in maxload for 99mph.
This is only 1 LI step lower then the Endurance of /75 LI 113 and can be explained by the /70//75 difference. SO HERE GOES MY SYSTEM GONE of 1 LI step difference/ 10kmph/ 6,3mph difference in speed for wich it is calculated.

Mayby in the smaller sises / there are exeptions to the rule, as I learned in time, so the sise has been given a maxload, different from what would be calculated with the gererally used formula.

This long story means that your tires dont need the lowering loadindex system I use. Then lower pressure could be totally safe and durable.

You would notice it then by bumping, so for instance rivets popping loose, with the LRD 73psi and LRE 79 PSI.

But as long as I dont know for certain , I stay with my advice in the beginning

[sourdough]

In response to sourdough's reply to my post, I wonder why manufacturers put MAX TIRE PRESSURE on their tires? I know the definition of MAX, but go ahead and run them down the road at MAX pressure and you will be exceeding the Manufacturer's MAX tire pressure. Makes sense to me.


They are max "cold" inflation pressures - not hot. Read the 2nd sentence in the Carlisle FAQ. None of the tire manufacturers state a max "hot" pressure that I know of simply because that number could be anything based on so many variables.

From TireRack:

Maximum Inflation Pressure

A tire's maximum inflation pressure is the highest "cold" inflation pressure that the tire is designed to contain. Cold conditions are defined as early in the morning before the day's ambient temperature, sun's radiant heat or the heat generated while driving have caused the tire pressure to temporarily increase.

For the reasons indicated above, It is also normal to experience "hot" tire pressures that are up to 5 to 6 psi above the tire's recommended "cold" pressure during the day if the vehicle is parked in the sun or has been extensively driven. Therefore, if the vehicle's recommended "cold" inflation pressures correspond with the tire's maximum inflation pressure, it will often appear that too much tire pressure is present. However, this extra "hot" tire pressure is temporary and should NOT be bled off to return the tire pressure to within the maximum inflation pressure value branded on the tire. If the "cold" tire pressure was correctly set initially, the temporary "hot" tire pressure will have returned to the tire's maximum inflation pressure when next measured in "cold" conditions.

Hopefully that clears up what the MAX pressure is - cold. The rest just "happens" and is normal.

[markjamestx]

Thanks for the clarification

[jadatis]

There is a difference between maximum(allowed) cold pressure and what most think is max pressure, pressure written behind AT on sidewall, or belonging to loadrange.

The pressure behind AT, will call it AT- pressure furtheron, is the pressure for wich the maxload is determined, for a speed , mostly max speed of tire, but not always.

The maximum cold pressure, is the maximum cold the tiremaker allowes.

The rising of pressure by higher temp in tire is all calculated in in the system, so no problem if pressure rises by driving .

Once read from one of the specialists here, that teststandards are used in tire-desighn, that they have to stand a pressure of 2 to 3 times the AT-pressure. This is for a AT 80 psi tire 160 to 240 psi!!!!!!

In earlyer days tiremakers allowed higher then AT , but nowadays not anymore.

But this all tells us, that you easyly can smuggle a bit with that AT pressure, if needed for laws of nature. Only dont do that with an already damaged tire by overheating , by using to low pressure for the load on tire,only once, then the mechanical forces that tear the beginning cracks furter, only get larger, and tire will fail sooner, and high pressure is blamed.

[CWtheMan]

Tire inflation pressures: There has to be a right way. Who defines the right way? Cold is cold. NHTSA defines cold tire inflation to be performed when the tires are cold,

If the vehicle has been setting in a covered garage for three hours, the tires are cold. If the vehicle has been parked at a campground at the Salton Sea for three hours, the tires are cold. If the vehicle is parked at Lake Tahoe for three hours, the tires are cold.

If the tires do not qualify for cold because they haven't set for three hours and you think the tires need inflation. Inflate them to the placard recommended inflation pressures. Later on, when the vehicle has had a chance to set for three hours, reset the inflation pressures.

[rcashdollar]

A couple of months ago I bought a Cougar xlite 21RGS which has the original tires 225/75R/15D on it (date code 2013). I put it away for the winter but will replace with E rated tires in the spring before we use it again. Talking to Discount Tire they tell me that they don’t even stock the D’s since all they ever do is use the E’s. They recommended the 80 PSI and I would think going form an 8 ply (D) to a 10 ply (E) would be a benefit too. I asked whether the wheels are okay going to E’s and he didn’t think twice about saying it’d work. Is this sound right?

[sourdough]

With the size of your trailer I would sure check behind the wheels and see what they are rated for before upping to 80 psi. I am assuming you are meaning 21 RBS? With 2013 tires I would be in the tire store before I did anything else with the trailer as far as going anywhere.

[rcashdollar]

Yes, 21RBS. I always thought the 5 year rule was crap and now I know better thanks to this forum. Like I mentioned I’ll put new tires on in the spring before we use it. I didn’t feel the need to buy new tires and let it sit there all winter.