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Old 10-04-2019, 10:57 AM   #1
Audionut
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Always 80 lbs psi in 'E' tires, or go by GVWR?

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.
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Old 10-04-2019, 11:00 AM   #2
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You can go by the load chart. I run 80 psi on my Carlisles.
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Old 10-04-2019, 11:09 AM   #3
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Originally Posted by flybouy View Post
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?
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Old 10-04-2019, 11:21 AM   #4
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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.
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Old 10-04-2019, 11:57 AM   #5
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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.
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Old 10-04-2019, 12:12 PM   #6
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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.
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Old 10-04-2019, 12:59 PM   #7
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Originally Posted by GMcKenzie View Post
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

Quote:

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.
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Old 10-04-2019, 01:10 PM   #8
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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.
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Old 10-04-2019, 01:33 PM   #9
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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.
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Old 10-04-2019, 01:36 PM   #10
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Also, what is the difference between an 'E' rated tire and LRE?
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Old 10-04-2019, 01:51 PM   #11
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And this is the load rating sticker on our camper.
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Old 10-04-2019, 01:54 PM   #12
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Quote:
Originally Posted by Audionut View Post
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.
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Old 10-04-2019, 01:59 PM   #13
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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".....
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Old 10-04-2019, 02:12 PM   #14
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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-w...lack-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.
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Old 10-04-2019, 02:15 PM   #15
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Quote:
Originally Posted by JRTJH View Post
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.
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Old 10-04-2019, 02:20 PM   #16
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Quote:
Originally Posted by Canonman View Post
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-w...lack-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.
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Old 10-04-2019, 02:24 PM   #17
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Originally Posted by Audionut View Post
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
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Old 10-04-2019, 02:51 PM   #18
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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?
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Old 10-04-2019, 03:06 PM   #19
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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.
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Old 10-04-2019, 03:15 PM   #20
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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/produ...-valve-han1600
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