stmar

Just got a set of Cooper AT3 265/70R17 tires. The stock tires on this truck are 255 per the door sticker and it specifies 35 PSI in front and rear. I have had 265's on it for as long as I have had it and have run 45 - 50 PSI. When I picked up the truck I found they had put 40 PSI in the new set of tires. I drove it and it does drive good so no complaints. What are other people with this size tire running? I went with the 6 ply instead of the 10 since I don't use this truck for anything strenuous, mostly highway.

Scuba_Dave

I inflate to what the door sticker indicates

stmar

Even when you change the stock tire? That is my confusion: sticker or adjust for the different tire??
The tire guys put it at 40 which is between the door sticker (35) and what I usually run in them (45 - 50).

screamineagle

That's fine if your running stock size.

To answer the OP, I would go by what the sidewall says. If it says 50 psi max I would run between 40-45 psi.

Rockjock3

The PSI on the door frame is only accurate on the same tires that the vehicle came on. You can use that pressure, but your mileage and wear can suffer.

I put my 295/70r18s on my truck and did the "chalk test" on them. I drove around until my tires were good and warm then I ended up at the back of a local school that has a long road. I got some children's sidewalk chalk and rubbed big fat lines from inside to outside on a front and rear tire. I then drove forward about 100 yards. I got out of the truck and checked the chalk that was left.

If it was gone in the middle I let a few PSI out. If it was gone on the edges then I added a few PSI. I had a portable compressor, but you could simply put more air in the tire than you need and go down from there.

When I got to a perfect wear pattern in the chalk, even chalk left across the whole tread, I used that pressure.

For my tires and truck that is 44/40 front/rear. The truck rides great and I put those numbers on my door sticker. Once a month I check my tires when they warm, usually when I get home from my work on my 20 mile commute, and top off if needed.

JimmyB1232

I have a 35" 10 ply and I have the rears at 30 and fronts at 34. If I drive long distances or pulling a trailer or have a good amount of weight in the bed I bump up the pressure and if I'm in the mountains I lower the pressure down to 28 all around. I'd just adjust the pressure to what feels best to you. When I go above 30/34 psi with no extra weight it just feels stiff and rough with every little bump, if I go lower than 30/34 then the steering feels mushy and sluggish.

techrep

iTrader: (1)

40 PSI Winter/ 50 PSI Summer

stmar

Interesting, is that because you want more traction in winter so a softer/less air tire? I guess the 40 is a good place to start and to quote Game of Thrones: "Winter is coming"!!!!!!

BassAckwards

According to my load index chart you need no more than 40 psi, and depending on your GVWR you can have no lower than 35psi.

Edit: if you can give me your GVWR I can give you a better idea of what to set it at because on any of our non HD trucks 40 is way more and will only harsher the ride.

stmar

GVWR = 6950 lbs
Thanks that would be helpful.