Tire PSI and truck camper question

OK so now Im confused. Can I up the back to 51 PSI or not? Im not an expert. I was going to but after reading the last post, Im not so sure. Thank you.

Listen clearly. There were questions asked and you didnt answer.

You can put whatever pressure you want in the tires you have from the 35psi whats on your door tag to the 51 psi on the side wall.

Here is the thing though.

1. If you have P rated tires the side wall max load rating on the sidewall gets derated some 9%.

That was 2238 lbs per tire. Not the 2460 it states on the sidewall.

Those P rated tires will carry that derated weight whether you put 35 psi in or 51 psi in the tires.

51 psi may stiffen the tire up some but its still a 2 ply sidewall marshmellow.

You will not get a higher rating on a p rated tire running more air in it.


2. Now if they are LT tires then @ 51 psi you will carry the full load of what the side wall says of 2460 lbs.

LT tires have inflation charts. 2460 @51 psi, 2200 lbs @ 44 psi, 1950 lbs @ 40 psi, etc etc...

Example:

LT 265/70/17 or 265/70/17. Same tire but different because of the "LT" on the sidewall. You also may have an "XL" on the side wall.

But if you dont want to tell us then go ahead and put 51 psi in the tires.

I guess it dont matter.

For my P rated tires of a 35 psi door tag I put 40 psi in when towing. My max on sidewall is 44 psi.

When I put the LT tires on when these wear out I will inflate to the max 44 psi on the side wall when towing.

robertjp wrote:

jadatis wrote:
Your tires are most likely Standard load P-tires, and on those they only give maximum allowed cold pressure.
The maximum load of tire can be carried up to 99m/h AT 35 psi , wich is standard reference-pressure for P-tires SL. So if you drive only below 99m/h you may use the 35 psi.

The space between 35psi and 51 psi is used to highen up the referce-pressure ( further AT-pressure) for higher speed then 99m/h with a system depending on speedcode of tire. Also for alighnment camber angle above 2 degr.

LT tires give on sidewall the AT-pressure , and in earlyer days higher was allowed and even adviced upto 10 psi extra, but nowadays the tiremakers dont allow it anymore, and so the AT-pressure is the maximum allowed cold pressure.

So tiremakers allow for SL P-tires a higher pressure then AT, and if you use it to cover some higher load on tire then maximum load, they cant prove you did it for that higher load then max ,that they dont allow, but mother nature will be happy with it.

To high pressure gives that less deflection of tire, that things go bumping, so to high is not bad for the tire, but bad for your kidneys and teeth-fillings.

OK so now Im confused. Can I up the back to 51 PSI or not? Im not an expert. I was going to but after reading the last post, Im not so sure. Thank you.

A lot of irrelevant info. No need to overthink it. Yes they say 51 psi You can and should put 51 psi in them when hauling a heavy load.
Check out a load v inflation chart for tires, any tires. You'll see the relationship of capacity relating to pressure. But it's not rocket science. You have 2500lb cap tires you're putting at least 2000 lbs on each. You should be in the upper end of the max psi for the best performance for that load.
Some of that above confuses me too........

jimh425 wrote:
I'd probably look at load inflation charts for those tires, but the tires won't be worse for wear at max pressure. The handling will be different, and you could get some abnormal tire wear especially when unloaded.

The tire ratings in the door are designed to give you a guide for what is the pressure you should run at sticker max GVWR.

Would have to double check it, but all my vehicles do have double chart for light load and heavy load.
Good tire manufacturers will publish charts with recommended pressure at given load.
If you can't find one, rule of thumb is to inflate to the same % of max pressure what % of max load you are carrying.
Than again - all you will loose riding at max tire pressure is comfort, while you will save fuel .

jadatis wrote:
Your tires are most likely Standard load P-tires, and on those they only give maximum allowed cold pressure.
The maximum load of tire can be carried up to 99m/h AT 35 psi , wich is standard reference-pressure for P-tires SL. So if you drive only below 99m/h you may use the 35 psi.

The space between 35psi and 51 psi is used to highen up the referce-pressure ( further AT-pressure) for higher speed then 99m/h with a system depending on speedcode of tire. Also for alighnment camber angle above 2 degr.

LT tires give on sidewall the AT-pressure , and in earlyer days higher was allowed and even adviced upto 10 psi extra, but nowadays the tiremakers dont allow it anymore, and so the AT-pressure is the maximum allowed cold pressure.

So tiremakers allow for SL P-tires a higher pressure then AT, and if you use it to cover some higher load on tire then maximum load, they cant prove you did it for that higher load then max ,that they dont allow, but mother nature will be happy with it.

To high pressure gives that less deflection of tire, that things go bumping, so to high is not bad for the tire, but bad for your kidneys and teeth-fillings.

OK so now Im confused. Can I up the back to 51 PSI or not? Im not an expert. I was going to but after reading the last post, Im not so sure. Thank you.

I always run my rears at the maximum sidewall pressure, in my case 80 PSI, with screw down valve stems not rubber ones... that eventually rot. Front's at recommended OEM pressure, in my case again, 60 PSI and screw down stems again.

Your tires are most likely Standard load P-tires, and on those they only give maximum allowed cold pressure.
The maximum load of tire can be carried up to 99m/h AT 35 psi , wich is standard reference-pressure for P-tires SL. So if you drive only below 99m/h you may use the 35 psi.

The space between 35psi and 51 psi is used to highen up the referce-pressure ( further AT-pressure) for higher speed then 99m/h with a system depending on speedcode of tire. Also for alighnment camber angle above 2 degr.

LT tires give on sidewall the AT-pressure , and in earlyer days higher was allowed and even adviced upto 10 psi extra, but nowadays the tiremakers dont allow it anymore, and so the AT-pressure is the maximum allowed cold pressure.

So tiremakers allow for SL P-tires a higher pressure then AT, and if you use it to cover some higher load on tire then maximum load, they cant prove you did it for that higher load then max ,that they dont allow, but mother nature will be happy with it.

To high pressure gives that less deflection of tire, that things go bumping, so to high is not bad for the tire, but bad for your kidneys and teeth-fillings.

robertjp wrote:
Yes 2460 lbs max load on the tire rating. Im assuming this is in addition to the truck?

again if they are P rated tires then they get derated about 9%..

your 2460 is 2238 lbs @ 35psi. It dont matter if you put 51 in there except it will stiffen the side wall.

If they are LT tires then its 2460 @ 51 psi...

What does the tire say on the side wall? Does it have an LT written before the tire size? Or an XL rating?

Better yet just tell us the make, model size of tire. we can look it up..

Yes 2460 lbs max load on the tire rating. Im assuming this is in addition to the truck?

51 would be the number with a load. Thise tires are rated for like 2500lbs or so, correct?
Empty 1/2 ton you have about 2500lbs on the rear axle. Add the camper puts you pretty close to max.
Front axle likely won't have much addl weight, depending on the campers center of mass, but the stiffer handling will be welcome so I'd run the fronts at the max too.

OK since I am a newbie to truck camping can anyone tell me what would be a good psi if the max is 51 and the camper weighs say 2,000 lbs? Also would the back be higher than the front? Thank you for all your replies. You guys are awesome!