I have a 2007 Tahoe, and I just replaced the factory 17" wheels with factory 18" wheels from a '08 Yukon. The recommended cold tire pressure on my 17's were 30 psi, according to the sticker on the driver's door. What is it for the 18's? Same?

 

I would go about the same. I have 32-35 on my 20's.

 

Rememeber the Firestone\Ford incident?

ALWAYS fill your tires to what is rated on the tire sidewall. Not what is labelled on the tire placard in the vehicle. Especially if you are changing wheels from what came stock. Tire pressures should be molded into the rubber.

 

I thought the molded tire pressure was maximum, not what you were supposed to inflate to. The Ford incident was where what they told them was too low and done for ride comfort. That was coupled w/ people that then didn't keep them inflated to even that low level. Most of the problems seemed to occur in the southern part of the country in the summer time at hwy speeds.

 

I like to run 34-35 psi in my vehicles but that is a personal choice. With must tires having a 44psi max it just depends on what you like. I like a higher tire pressure for fuel economy and having to check it less.

 

I keep mine at about 30psi and have the factory Bridgestones still.
I would adjust the psi to something that will keep the tread liner across the tire without exceeding the max psi.
too high and its wearing too much in the center of the tire,too low and its wearing on the outside edges.

 

I run 34 in mine. I've noticed now after a couple of rotations that the outer edge on the fronts isn't feathering anymore.If you put the max pressure in cold, then it will be exceeded as soon as the tire warms up.

 

You're right, it is the maximum pressure...going over the molded tire pressure is a BAD idea. It's safe to stick with what appears on the door/manual as long as its under the molded pressure. You can go under safely roughly 5 PSI, all depends on your regular load and type of tire. If you go anymore under this then you'll risk wearing your tires more quickly and oddly and, in worse cases, this can destabilize your tires at high speeds and high tensions.

 

the best way to decide on a tire pressure is to get some chalk color a section of tread on the tire all the way across find a flat straight section of road. then drive straight. if it has worn off on the outer edges then the pressure is to low if it wears of in the center you have to much pressure and if it has worn off evenly then you are good

 

That works great for spirited driving (read autocross) but not sure if it would yield good results for street driving. For example, when autocrossing I ran 40-42 psi hot but used about 30 psi cold for street driving. I used the chalk method only just marked about every 120* around the tire. I would be concerned that it would yield too high a pressure for street driving but could be wrong. Will have to give it a try when it dries off here.