Trailer Wheel PSI Ratings

[GaryWT]

Well OK, it is true I have not been able to think straight for a week and this all just confused me and I guess as a result I was confusing others. Thanks for interpreting things Javi...

For me when you install new tires it is rubber on existing rims and wheels are new rubber on new rims. But as stated in reality rims and wheels are basically the same thing I guess.

So you do learn something everyday and I find it interesting that the rims have various ratings, never knew this. For me I do not thing I have to worry since my trailer is under 8,000 pounds and my tires only go up to 65psi. No rim problems in 3 years so let's hope that continues

[PARAPTOR]

Okay here is the configuration I have and feel comfortable with given my 7K axles;
Carlisle ST235/85R16 F tires rated 3960 LBS @ 95 PSI,
SENDEL 8 lug rims 3750 LBS Max 110PSI,
setting my Tire Minder to alert at 108 PSI which will allow for about a 14% pressure rise and still be below the rims 110PSI

If any thing may drop the tire PSI a few pounds for a smoother ride, will see how this works out on rest of the way home.

Do not see how you can make Sailuns @ 110PSI work without different rims ???

Have to say this has been a memorable trip into the OKLAHOMA/Texas Area (Tornado Warnings, Flooding/Winds). Well at least I now know the Raptor can be wind and water certified.

Current issue is to watch out for Alligators spotted on perimeter of camp ground and in near by flood made ponds. Now that roads are opening slowly working my way North (less excitement)

[gearhead]

Originally Posted by PARAPTOR

Okay here is the configuration I have and feel comfortable with given my 7K axles;
Carlisle ST235/85R16 F tires rated 3960 LBS @ 95 PSI,
SENDEL 8 lug rims 3750 LBS Max 110PSI,
setting my Tire Minder to alert at 108 PSI which will allow for about a 14% pressure rise and still be below the rims 110PSI

If any thing may drop the tire PSI a few pounds for a smoother ride, will see how this works out on rest of the way home.

Do not see how you can make Sailuns @ 110PSI work without different rims ???

Have to say this has been a memorable trip into the OKLAHOMA/Texas Area (Tornado Warnings, Flooding/Winds). Well at least I now know the Raptor can be wind and water certified.

Current issue is to watch out for Alligators spotted on perimeter of camp ground and in near by flood made ponds. Now that roads are opening slowly working my way North (less excitement)

Come on back down here again sometime. Don't look back, tropical storm Bill may catch you.
My son had a gator in his yard after his dogs. It won't be back. I saw a big one next to the highway last week. I wouldn't be surprised to have one in my yard.

[audio1der]

Interesting thread. I spoke with a rep at Tredit who make our A162 wheels and he confirmed by email they would safely take 65psi/1900lbs.
But when we received our Kumho radial 857's, the wight rating is max'd at 69psi, not 65. The tire shop who swapped them inflated to 69.
While installing our TPMS sensors (I'm a safety geek) each tires settled to 68psi cold. They rose to 76/77psi on the sunny side while driving. It occurred to me that is measurably higher than Mr. Tredit told me was safe.
We are well underweight for all our suspension and tires- I'm thinking if we start at 67/68psi it will rise to whatever it wants to rise to and we'll be fine.
Am I off base?

[bsmith0404]

Originally Posted by audio1der

Interesting thread. I spoke with a rep at Tredit who make our A162 wheels and he confirmed by email they would safely take 65psi/1900lbs.
But when we received our Kumho radial 857's, the wight rating is max'd at 69psi, not 65. The tire shop who swapped them inflated to 69.
While installing our TPMS sensors (I'm a safety geek) each tires settled to 68psi cold. They rose to 76/77psi on the sunny side while driving. It occurred to me that is measurably higher than Mr. Tredit told me was safe.
We are well underweight for all our suspension and tires- I'm thinking if we start at 67/68psi it will rise to whatever it wants to rise to and we'll be fine.
Am I off base?

Based on my understanding of the SAE testing, your 65 psi rated wheels were probably tested around 70-75 in order to obtain that rating. The wheel manufacturer will not tell you it's safe to run more than the 65 they are rated at. In my mind, knowing they were tested above that, the big question is how long will they safely hold up to higher pressures? I don't know the answer and I doubt you will find anyone who will tell you, even if they know.

[PARAPTOR]

[QUOTEamp sites=gearhead;175794] Come on back down here again sometime. Don't look back, tropical storm Bill may catch you.
My son had a gator in his yard after his dogs. It won't be back. I saw a big one next to the highway last week. I wouldn't be surprised to have one in my yard.[/QUOTE]

gearhead; Yes, this trip has been an experience to say the least. People we have met in the Oklahoma/Texas area are super!! Very laid back and friendly Recall some moments like calling ahead before moving between camp sites trying to avoid the bad weather (Flooding and Tornado Warnings) and hearing "we have some flooding and only couple roofs blown off" OKAY

Some camp site discussions are about drones, after being in this area for a while do not see it ever being a problem annoying people in this region.

"Dear, there is a drone out here, into the house, back on the porch, DRONE GONE and issue resolved "

Getting more Alligator spotting on/near camp site. Pulling out soon. Memphis traffic next excitement.

[bsmith0404]

I just got a response back from Carlisle. They stated the 235/85R16 F tires I have on my RV will safely carry 3640 at 80 PSI, which is still well above my weight on wheels. They are rated for 3960 at 95 so I can safely reduce the air pressure a few lbs to keep them under the max of 100 for the wheel. They also recommended using nitrogen so I can run higher pressures at a more stable/constant pressure.

I'd still like to go to a heavier wheel, but for now I'm going to drop the air pressure to 90 cold.

[gearhead]

Originally Posted by bsmith0404

I just got a response back from Carlisle. They stated the 235/85R16 F tires I have on my RV will safely carry 3640 at 80 PSI, which is still well above my weight on wheels. They are rated for 3960 at 95 so I can safely reduce the air pressure a few lbs to keep them under the max of 100 for the wheel. They also recommended using nitrogen so I can run higher pressures at a more stable/constant pressure.

I'd still like to go to a heavier wheel, but for now I'm going to drop the air pressure to 90 cold.

Good news. At least there is a plan "B".

[CWtheMan]

Originally Posted by bsmith0404

I just got a response back from Carlisle. They stated the 235/85R16 F tires I have on my RV will safely carry 3640 at 80 PSI, which is still well above my weight on wheels. They are rated for 3960 at 95 so I can safely reduce the air pressure a few lbs to keep them under the max of 100 for the wheel.

I'd still like to go to a heavier wheel, but for now I'm going to drop the air pressure to 90 cold.

In the context you have provided Carlisle can make such recommendations.

The FMVSS standard for tire and rim fitments only apply to the original equipment fitment. The regulation requires the tire be fitted to the appropriate rim. That would be one that supports the tire’s maximum load capacity and the inflation psi needed to provide that load capacity.

Carlisle reps have a tendency to bend their own rules. If you will look at Carlisle’s “best practices” PDF you will find that they never recommend less than maximum load capacities from their tires unless something lower is set by, or recommended by, the vehicle manufacturer to be lower than max.

IMO Lowering tire pressures to gain a “softer” or “better” ride is like asking for an unscheduled rest stop along some highway or byway.

CW

[bsmith0404]

Carlisle knows that I have rims that have a max 100 psi and max weight of 3580. They are also aware that I have about 12500 lbs weight on wheels with 4 feet on the ground. They had all pertinent information to make the recommendations that they did. They basically just told me nitrogen would be a good option, but the tires can support 3640 at the lower psi.

I wouldn't be lowering them for a softer ride, I am lowering them to safely stay within the psi limits of the wheels.

I've also seen other charts put out by some tire manufacturers that give different loads at different psi for the same tires.

[gearhead]

Originally Posted by bsmith0404

Carlisle knows that I have rims that have a max 100 psi and max weight of 3580. They are also aware that I have about 12500 lbs weight on wheels with 4 feet on the ground. They had all pertinent information to make the recommendations that they did. They basically just told me nitrogen would be a good option, but the tires can support 3640 at the lower psi.

I wouldn't be lowering them for a softer ride, I am lowering them to safely stay within the psi limits of the wheels.

I've also seen other charts put out by some tire manufacturers that give different loads at different psi for the same tires.

I'll beat on this dead horse some more.
I think you're good to go Brent.
Think of it this way...(acknowledging that there IS a difference in ST & LT tires) My Ford door sticker tire inflation numbers are 65PSI front, and 80PSI rear. Obviously, to me anyway, the rears are higher for load carrying capacity. And of course the rear tires and front tires are the same brand, model, etc. Do I drive around town with no load and my rear tires at 80PSI? No. I usually run all of them 65-70. When I load up the 5th, I bump them up. Higher pressure for higher loads.

[audio1der]

Hmmm. I was quasi-aluding to this earlier; I think I should be able to safely run 65psi and allow the pressure to rise without worry. Starting at 69/69 may be a little too much.

[Desert185]

Regardless of what we've discovered in this thread, its hard for me to believe that setting the max tire inflation pressure cold will create issues because of increased pressure due to rolling temperature rise. Logic would dictate that this completely understood phenomenon would be taken into account by those who design wheels for the pressure rating of tires to be used on their wheels.

This smells of lawyer speak more than anything else, but I'm just a suspicious consumer trying to understand the suspension/wheel/tire capability of my trailer. After all this time, we're re-inventing the wheel, so to speak?

[CWtheMan]

Originally Posted by gearhead

I'll beat on this dead horse some more.
I think you're good to go Brent.
Think of it this way...(acknowledging that there IS a difference in ST & LT tires) My Ford door sticker tire inflation numbers are 65PSI front, and 80PSI rear. Obviously, to me anyway, the rears are higher for load carrying capacity. And of course the rear tires and front tires are the same brand, model, etc. Do I drive around town with no load and my rear tires at 80PSI? No. I usually run all of them 65-70. When I load up the 5th, I bump them up. Higher pressure for higher loads.

The recommended tire pressures for your truck are, as you say, found on the tire placard or in the vehicle owner's manual.

As written in the FMVSS, tire pressures for automotive vehicles MUST provide a percentage of load capacity reserves. The vehicle manufacturer is responsible for doing that with air pressure when they set the recommended inflation pressures.

RV trailer tires are not required to have any load capacity reserves. Because the ST tire manufacturers recommend that their tires should always be set at full sidewall pressures the trailer manufacturers will use the minimum tire requirement and set their inflation pressures at sidewall max. It's almost a 100% industry standard for ST tires.

CW

[CWtheMan]

Originally Posted by Desert185

Regardless of what we've discovered in this thread, its hard for me to believe that setting the max tire inflation pressure cold will create issues because of increased pressure due to rolling temperature rise. Logic would dictate that this completely understood phenomenon would be taken into account by those who design wheels for the pressure rating of tires to be used on their wheels.

This smells of lawyer speak more than anything else, but I'm just a suspicious consumer trying to understand the suspension/wheel/tire capability of my trailer. After all this time, we're re-inventing the wheel, so to speak?

You're correct, and it's called thermal equilibrium. When using that term in conjunction with tires you can search and find the mathematical formulas.

CW

[PARAPTOR]

Okay pulling out in the morning, because of the lack of phone service here, I could not call any vendors to see what the latest story is

So here is the final configuration I decided to go with for the Raptor:
GVWR 16,500 with 7K axles;
Carlisle ST235/85R16 F rated tires ----- 3960 LBS @ 95 PSI, (Pumped to 95 PSI)
SENDEL T08 8 lug rims (wheels) rated at 3750 LBS and Max 110 PSI,
Set my Tire Minder to alert at 108 PSI which will allow for about a 14% pressure rise and still be just below the rims (wheels) 110 PSI

On the trip north, I will see if I get any alarms, as well as, periodically monitor the max PSI

[CWtheMan]

Originally Posted by PARAPTOR

Okay pulling out in the morning, because of the lack of phone service here, I could not call any vendors to see what the latest story is

So here is the final configuration I decided to go with for the Raptor:
GVWR 16,500 with 7K axles;
Carlisle ST235/85R16 F rated tires ----- 3960 LBS @ 95 PSI, (Pumped to 95 PSI)
SENDEL T08 8 lug rims (wheels) rated at 3750 LBS and Max 110 PSI,
Set my Tire Minder to alert at 108 PSI which will allow for about a 14% pressure rise and still be just below the rims (wheels) 110 PSI

On the trip north, I will see if I get any alarms, as well as, periodically monitor the max PSI

The Sendel TR8 rims are rated at 3960# at 110 psi.

http://sendelwheel.com/wheels/tr8..

CW

[audio1der]

Originally Posted by PARAPTOR

Okay pulling out in the morning, because of the lack of phone service here, I could not call any vendors to see what the latest story is

So here is the final configuration I decided to go with for the Raptor:
GVWR 16,500 with 7K axles;
Carlisle ST235/85R16 F rated tires ----- 3960 LBS @ 95 PSI, (Pumped to 95 PSI)
SENDEL T08 8 lug rims (wheels) rated at 3750 LBS and Max 110 PSI,
Set my Tire Minder to alert at 108 PSI which will allow for about a 14% pressure rise and still be just below the rims (wheels) 110 PSI

On the trip north, I will see if I get any alarms, as well as, periodically monitor the max PSI

Pararaptor- is your pin weight 2500lbs? (2 x 7K axles with a GVWR of 16,500)

[PARAPTOR]

Originally Posted by CWtheMan

The Sendel TR8 rims are rated at 3960# at 110 psi.

http://sendelwheel.com/wheels/tr8..

CW

I have pictures of my wheel 3750 lbs at 110 PSI (previous post). Did not take picture of other stamping but did use a small mirror the other day to see other stampings and as far as I can tell they were stamped "TO8" and by the picture on the sendel site (see link) looks like them.

http://sendelwheel.com/wheels/t08bmls


Response to other post:

GVWR is not all on axles (pin weight plus axle) Raptor Pin weight is over 3K

[PARAPTOR]

Okay, here is some information I have gathered so far

So far no Tire Minder alarms (set point 108 PSI). Highest tire pressure seen was 106.3 PSI traveling AT 65MPH with outside ambient temps 95 plus. That's a PSI rise of around 11 and close to a 12% rise. At this tire pressure I was at around 97% of the Max Wheel (rim) pressure of 110PSI. Real close to Max and closer than what I would like to be. Unfortunately co-pilot did not get tire temp. Sometime when you try and push your luck you get nothing

if I would have started out with a tire requiring 110 PSI, a standard 110 PSI max rated wheel (rim) would have experienced around 123 PSI, 12% greater than the Max pressure