tire pressure

Just put a set of 265/70/17 Cooper AT3's on my 2010 Z71 1/2 ton. On the door of the truck it says 35 psi. I pull a 21' Ranger. I weighed it and it is around 4800#s with a tournament load and fuel. Was wondering what air pressure should I be running? Want to get the best performance out of them.

35

Have you done a chalk test? Where you draw a line across the tread then drive a bit and see if the chalk is erased evenly? It should be erased evenly from inside edge to outside edge. If the middle is erased and the edges are not, decrease pressure. If the opposite is the case increase pressure.

If the tire is the exact same as the OEM, then follow the door sticker.

straight from Ford.
https://www.ford-trucks.com/how-tos/a/ford-f150-f250-how-to-determine-proper-tire-pressure-355594

Excellent choice in tires, I might add.

thank guys. just wondering because i checked them the next day and they put 40psi in two and 35 in the other two.

Chalk test is what you need. The fronts should end up being a few pounds higher than the rears. By the standardized systems P rated tires are suppose to be able to carry their maximum rated weight at an inflation of 35 psi.

In my pickup I run around 40 in the front and 35 in the rear on similar tires with a 1/2 ton 4x4.

thanks

I always run mine based on the recommendation on the tires themselves. I run Hankook's and they list the max pressure at 40 and that is where I run them. Never had a problem, the ride is a little stiffer than running at 35 but helps with the load carrying.

If your not loaded to max weight all the time running max PSI will decrease tread life.

Funny my 50000 mile tires always last nearly that long. But to each his own

Your right, I'm LOL

Have a set of 50k mile tires with 30k miles on them that are way over 50% tread left and a set of 60k tires with 70K on them that are about 50% tread left... running max inflation is NOT the best answer.

So you are saying your "50k mile" tires are almost lasting to the end of their warranty period???!

They should last LONGER than the 50k mileage warranty. Haha if you inflated them properly, they should.

Heck, I'm lucky to get 40k.

I run my tires 5psi below max recommended rating on the tire. Trailer tires are inflated to provide a full contact patch on the ground, similar to the chalk test mention earlier in this thread.

Simple:
Always inflate tires when cold.
Assuming tire are same size, go with door sticker.
Door sticker psi is designed for max payload/towing.

Complicated:
Assuming you have the same size or similar size tire, go with the door sticker. In general, I think pickup truck tire psi are the same from front to back. If you rarely haul or put heavy things in the bed of the truck, you could potentially drop the rear psi 1-2. Remember to inflate when cold, like the start of a day or something. The door sticker psi is designed to handle full payload. There is no need to increase tire psi when you put a heavy load, unless it's extremely overloading the truck that you're on the bumper stops with the tires bulging... Your best bet in a scenario like that would to put the tire at max psi and hope for the best.

I've also noticed that tires are never run at full psi. (Maybe a big rig is the exception or dually?) Running tires overinflated is bad for handling and braking, and tire wear. My dad will bring up how his tire arn't that good and spinning wheels in the rain. For some reason he insists on having a higher psi then the sticker, even though I've told him multiple times.

Whatever the sidewall says!

Door sticker says 30#. I set at 30# cold and after driving about 20 miles they heat up to 35#.

Sidewall is max PSI. Works well on trailers but best way on vehicles is to start with door sticker and chalk test or gravel road test.