Previously, I asked the members for their thoughts and opinions on which LT tires I should replace my stock 275/65/18 P rated tires with. I decided on the 275/65/18 Cooper AT/3's and they will be installed on Sept. 3rd. On the door of my F150, it shows 35psi. Is that where I should have the Cooper tires at or is that what the original tires are supposed to be at? And, when I tow, where would I have the psi at? thanks in advance!

Weigh the truck to see how much weight is on each wheel then go to Coopers web site and get the psi for that wieght.

You could also do the old reliable "chalk test".take the truck to a large, relatively empty parking lot. Make a chalk mark across the tread of each tire. Drive the truck a hundred yards or so. Look at the chalk marks. If the mark is worn evenly across the full width of the tread, the inflation pressure is just right. If the chalk is worn mostly on the sides of the tread, the inflation pressure is too low. If the chalk is worn mostly in the center of the tread, the pressure is too high.

I do a variation of the chalk test with wide masking tape. Put it across the tread and drive a few miles before looking at it. Adjust inflation until the wear is slightly biased to the middle for everyday driving.Sidewall max pressure when towing anything heavier than a 5000# utility trailer.

OP...unclear if you are asking information on PSI for a 'P' class or 'LT' classtireYour door label is only for a 'P' class tire of THAT SPECIFIC SIZE: P275/65R18Load rating 114 with a speed rating 'T'Now for the next higher class, 'LT', that label info is wrong

Those are LT tires. When I had my F150 I ran some LT Michelins. I ran the door PSI unloaded and ran 45PSI towing. Discount Tire said 44 PSI was all that's needed to match the trucks RAWR. I tried 50 PSI a couple times and there was really no difference and the ride was harsher.

TV Tire Pressure Question | Good Sam Community

14 Replies

BenK
Explorer
Sep 02, 2014
OP...unclear if you are asking information on PSI for a 'P' class or 'LT' class
tire

Your door label is only for a 'P' class tire of THAT SPECIFIC SIZE: P275/65R18
Load rating 114 with a speed rating 'T'

Now for the next higher class, 'LT', that label info is wrong
Sport45
Explorer II
Sep 02, 2014
I do a variation of the chalk test with wide masking tape. Put it across the tread and drive a few miles before looking at it. Adjust inflation until the wear is slightly biased to the middle for everyday driving.

Sidewall max pressure when towing anything heavier than a 5000# utility trailer.
mowermech
Explorer
Sep 01, 2014
You could also do the old reliable "chalk test".
take the truck to a large, relatively empty parking lot. Make a chalk mark across the tread of each tire. Drive the truck a hundred yards or so. Look at the chalk marks. If the mark is worn evenly across the full width of the tread, the inflation pressure is just right. If the chalk is worn mostly on the sides of the tread, the inflation pressure is too low. If the chalk is worn mostly in the center of the tread, the pressure is too high.
K_Charles
Explorer
Sep 01, 2014
Weigh the truck to see how much weight is on each wheel then go to Coopers web site and get the psi for that wieght.

Forum Discussion

TV Tire Pressure Question

14 Replies

About RV Tips & Tricks

Related Content

Tire Pressure?

Tire pressures

Tire pressures

tire pressure

Question about tire pressure