I recently purchased a set of 275 60 R20 Tires and my stock tires were 275 55 R20. My old tires ran at 35 PSI cold should i run the new tires at the same pressure? My concern is that my old tires had a max pressure of 51 and my new tires have a max pressure of 44 so in the Texas heat my tires easily run around 39 psi which to me makes me think they are going to wear out pretty quick. I (Yeah i know i know not a whole lot of a difference in size i was being cheap to save on gas mileage. LOL)

 

I'm in Texas and have 275/55/20" wheels and tires. I run 50lbs in the fronts and 48lbs in the rear for better traction since the back doesn't carry much weight. Tires are rated at 51lbs. Never had a problem with odd tire wear or tires wearing out. As a rule, tires are manufactured with a 15lb safety rating. You could conceivably run 66lbs in the old tires and 59 in the new, but it's not recommended. Tires are not going to pickup that much heat to make up that much pressure. If your tire brand is Yokohama, I've had a bunch of experience with them. You'll either max out the tire pressure or pay dearly at the gas pump. Made a 27% difference in gas mileage on my last truck.

 

Run them at the pressure on the door jamb sticker unless that pressure is higher than max for the tires. Those are cold pressures.

 

My tires are low profile tires and I run my fronts at 40 psi and the rears at 36 psi even thought the door sticker says otherwise.
I put tire dressing on and drive it around a bunch of corners. When it stops taking the dressing off the edge's i'm good.
I don't want bald edges before the rest of the tires wear. I also pay close attention to the tread in the center of the tire due to
higher PSI to make sure I'm good. everyone has the own little thing they do to get it the way they want. This is mine.

 

If the new tires are P metric I would run them at 35 psi cold which is probably what the sticker on the door jam recommends. The pressure increasing to 39 psi after driving is perfectly normal and designed to do this and will not decrease tire wear.

The rule of thumb is that for every 10 degrees of air temp change your tires can lose or gain 1 psi.That is why checking tire pressure regularly will extend your tread life.