Tire PSI and truck camper question

Grit dog wrote:

lawrosa wrote:

Grit dog wrote:
Yes you can air up to what the tire says.
Your little camper will be about 2000lbs if your lucky. Get any flavor of load range E tires so you can stiffen up the back. Will be a much better ride in your half ton. And you can air back down to 35psi when you don't have the camper.

Isnt that bad advice telling him to put a load range E on a truck with P rated tires ( most likely) and rims?

Rims are not rated for those higher pressures, and the idiot at the store will probably not be smart enough to put rigid valve stems on too.

Since you're the tire expert, how do you know the rims aren't rated for a higher pressure? I can't dispute that with Internet data, no can I dispute the 9% de rate thing I guess . Which is also some buried away in the books theory by the tire industry I guess? Also mentioned dropping another 20% to get to the "full time" weight rating vs the "max load" rating. By the time you do all that, the tire won't hold the vehicle itself p, almost. Found a couple articles discussing it, but if it was real, trucks with P tires would come with a big placard on the dash warning that the tire ratings ON the tires was not valid.

Maybe I'm just ignorant and lucky, but I've been putting D or E load tires on half tons for going on 30 years. Even running 60-70-80 psi at times hauling loads way to heavy for the trucks' ratings never popped a rim.

Yours and capris paragraph of theory are akin to the vehicle weight cops except you're tire weight cops.
Unless you can cite some real over inflation catastrophies or something, I'll consider it internet drivel and not be concerned with E tires on my half ton.

Again, some folks on here live in the real world, others will reccomend 1 ton duallies to pull pop up campers.

And FWIW, the new HD Rams have "soft" valve stems with 80 psi tires. Worked fine for years now.

Well im not the tire expert. Only from what I read from the FMVSS..

When P-metric or metric tire are installed on light trucks (SUV, pickup or minivan), the load
rating/capacity of the tire is reduced by a factor of 1.10 as prescribed by the Federal Motor
Vehicle Safety Standards (FMVSS). This load reduction is mandated by Federal motor Vehicle
Safety Standards (571.120). This is based on the expectation that passenger type tires (Pmetric)
tires which are designed mainly for passenger cars may experience more severe use
and overloading when used on light trucks.


https://www.nexentireusa.com/cms_files/original/NEXEN_TIRE_SAFETY_BULLETIN___REPLACING_LT_TIRES_ON_LIGHT_TRUCKS.pdf

From the FMVSS. Reading 2nd page in states the 1.10 / by


https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol6/pdf/CFR-2011-title49-vol6-sec571-120.pdf


The tires even derated must meet the axle rating of the truck.

So the OP's tires @ 35 psi can carry 2236 lbs. Thats 2460/1.10

Thats 4472.

But whats his axle rating?

2000 lbs on a rear thats already at say 2300 lbs your at 4300. Maybe ok for the tire and borderline.

But these chevy axles are rated lower and this is the problem....


Example my truck chevy 1500..

P rated tire sidewall 2535/1.10 = 2304lb tire rating ( 4608)
RAWR 3750.
Cat scale weight @ rear 2300 lbs
RAWR 3750-2300 1450lb payload.

No way can I put a 2000lb TC in my truck bed without going over axle weight.

mkirsch wrote:
It's not that complicated.

What most people are telling you here is that IT DOES NOT MATTER. 35PSI or 51PSI, those P-metric passenger car tires have the SAME LOAD CARRYING CAPACITY.

Try 35PSI and see if you like it. Try 51PSI and see if you like it better or worse. Try some pressures in between.

Unless you are just absolutely nerve-dead, you will know quickly if there are any problems. Use your common sense, TURN AROUND, and limp home if you don't like how things feel.

You're correct, it was determined that tires don't get stronger after 35, BUT they do get stiffer. 35 is a marsh mellow ride compared to 50. Hauling a high CG load like a camper, stiff suspension/chassis/tires rule.

lawrosa wrote:

Grit dog wrote:
Yes you can air up to what the tire says.
Your little camper will be about 2000lbs if your lucky. Get any flavor of load range E tires so you can stiffen up the back. Will be a much better ride in your half ton. And you can air back down to 35psi when you don't have the camper.

Isnt that bad advice telling him to put a load range E on a truck with P rated tires ( most likely) and rims?

Rims are not rated for those higher pressures, and the idiot at the store will probably not be smart enough to put rigid valve stems on too.

Since you're the tire expert, how do you know the rims aren't rated for a higher pressure? I can't dispute that with Internet data, no can I dispute the 9% de rate thing I guess . Which is also some buried away in the books theory by the tire industry I guess? Also mentioned dropping another 20% to get to the "full time" weight rating vs the "max load" rating. By the time you do all that, the tire won't hold the vehicle itself p, almost. Found a couple articles discussing it, but if it was real, trucks with P tires would come with a big placard on the dash warning that the tire ratings ON the tires was not valid.

Maybe I'm just ignorant and lucky, but I've been putting D or E load tires on half tons for going on 30 years. Even running 60-70-80 psi at times hauling loads way to heavy for the trucks' ratings never popped a rim.

Yours and capris paragraph of theory are akin to the vehicle weight cops except you're tire weight cops.
Unless you can cite some real over inflation catastrophies or something, I'll consider it internet drivel and not be concerned with E tires on my half ton.

Again, some folks on here live in the real world, others will reccomend 1 ton duallies to pull pop up campers.

And FWIW, the new HD Rams have "soft" valve stems with 80 psi tires. Worked fine for years now.

Yeah Im going to put 51 psi cold on the back and leave the front at 35. After reading all that it is confusing. Hope that is the right thing. Thank you

It's not that complicated.

What most people are telling you here is that IT DOES NOT MATTER. 35PSI or 51PSI, those P-metric passenger car tires have the SAME LOAD CARRYING CAPACITY.

Try 35PSI and see if you like it. Try 51PSI and see if you like it better or worse. Try some pressures in between.

Unless you are just absolutely nerve-dead, you will know quickly if there are any problems. Use your common sense, TURN AROUND, and limp home if you don't like how things feel.

All too complex for me. I just run maximum advertised (on the tire sidewall) cold inflation pressure, all the time on the rear and the OEM recommended inflation pressure on the front. Don't care about riding comfort, it's a truck, not a Coupe DeVille.

One more time - find manufacturer inflation chart and use it.

There seems to be some misconceptions about the max tire pressure listed on the sidewall of tires:

1) P type tires will only have 35psi, 44 psi, and 51 psi listed as the max (for Standard Load). Exceptions: Some tires are calculated in metric units and the max would be 36 psi, 44 psi, and 51 psi. Also Extra Load tires will have the max of 41 psi or 50 psi.

2) In all cases, Standard Load P type tires carry the max load at 35 psi (except metric calculated ones where it is 36 psi), even those labled with a max of 44 and 51 psi.

3) LT tires (radials) will have a max pressure of 50 psi, (Load Range C), 65 psi (LR D), 80 psi (LR E), etc.

Deleted

Grit dog wrote:
Yes you can air up to what the tire says.
Your little camper will be about 2000lbs if your lucky. Get any flavor of load range E tires so you can stiffen up the back. Will be a much better ride in your half ton. And you can air back down to 35psi when you don't have the camper.

Isnt that bad advice telling him to put a load range E on a truck with P rated tires ( most likely) and rims?

Rims are not rated for those higher pressures, and the idiot at the store will probably not be smart enough to put rigid valve stems on too.