what psi to use

[Nick1994]

Originally Posted By: Dallas69
I have 235-75-15 now and this is stock size.
The door info says 35 frt and 41 rear.
Man,the range in these replies is all over the place.
Thanks to all.
Go with CapriRacer, he's a long time Tire Engineer and I'd take his recommendation over anybody's for anything tires.

 

[gaijinnv]

Originally Posted By: CapriRacer
Man, you guys are all over the ball park.

Step 1) Find the vehicle tire placard. On Ford trucks, it's located on the driver's door. It will list the original tire size and the specified pressure for that size.

Note: Pickup trucks come in so many configurations that it is impossible to know what the vehicle tire placard says unless you actually look at it. Best guess for a 1987 F-150: P235/75R15 XL at 35 psi front/41 psi rear.

Step 2) Match the original load carrying capacity.

Note: On pickup trucks, vans, and trailer, P type tires have to derated in load carrying capacity by a factor of 1.1

So a P235/75R15 at 35/41 has a truck rated capacity of 1844#/1985# and inorder to carry that load a 31x10.50R15LT needss to use 37/42 psi.

OP: What does the vehicle tire placard say?


Originally Posted By: Dallas69
I have 235-75-15 now and this is stock size.
The door info says 35 frt and 41 rear.
Man,the range in these replies is all over the place.
Thanks to all.


Then you have your answer: 37psi Front / 42psi Rear.

HTH