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The OEM Goodyear tires that came on the '92 SSE were suggested to be kept at 28PSI per Pontiac. The tires wore perfectly at that pressure. When it was time to replace them, I went back with Goodyear again. They wore on the outside at 28. I had to keep them at 30-32PSI to get an even wear. All the sets since than I've had to keep at 30-32. The '05 SE I've had to keep at 32-35PSI to get even wear.

Any comments, observations, or personal experience? - BC

I run about 26 in the front and closer to 22 in the rear on my truck with 285/75/16's. If not I would wear the middles out in no time.

I don't go by the sidewall (meaning the max psi rating), I go by the contact patch and or the amount of load that will be on them. If I know I'm going to have a car load of people and stuff I will put more air in before a big trip. In my car I really haven't taken the time to get it all figured out, but I don't think I run a full 35, probably closer to 32psi.

With my '86 I had them aired up to the max 44psi. They wore perfectly flat across the tread pattern, and I see the same results with tires across the stable here. The only time I run less than the max psi that is at the track.

Penny's tires are always at 40. Wear is always nice and even.

I think it depends on the tire too. The old tires on my car were happy at around 28, but the Generals seem to wear best at about 34 psi or so.

I run 35psi in all the vehicles I own, never had any wear issues.

I was gonna say, you guys are running them fairly low. I too typically run between 32 - 35 psi. In the 'Burb, 44 is what the tire says as max, but in winter when I have the plow on and am carrying the additional ballast weight, I'll go closer to 50.

I typically run 40 in everything, I don't care if the inside wears slightly quicker then the outside, I prefer the way they ride and drive like that.

The max rating on the sidewall of the tire is the MAX recommend PSI from that tires manufacturer which includes the heat expansion that will raise pressures, for that particular tire.
It is NOT the recommended cold tire pressure.

Your cold tire pressures should be less than the MAX PSI rating on the sidewall of the tire.

I'm with Andrew, I run 35 psi in all the tires of all my vehicles, and have had excellent tire wear, even across the tread.

Also, keeping up on the rotations will help get the most out of your tires life span.

Lane, sounds like you need to be running LT tires on the 'burb running those pressures.

Those are LT tires. Come winter, I'm going to see if I can score some Tahoe/Suburban Z71 wheels. They're 17" and I can run a slightly bigger tire too (preferably BFG A/T's), giving me about 2" of additional lift, which is important when carrying around the plow. Western's Ultra-Mount setup, the quadrant portion of the frame and angle arms sit really low to begin with. Much lower than the old Uni-Mount setup. So add that, with ~800 pounds of plow weight, offset with 700 pounds of ballast and the torsion bars cranked up, I get about 5" of clearance. That's fine for most roads, but crossing rail intersections, I have to slow down and crawl over. And then when plowing at the house in West Chicago, coming out one end of the alley, I scrap the skid plate on the angle arms.

So yea, every inch I can get, even by adding an extra PSI or two, helps.

I may be over-cautious, but running normal street tires at 40-psi plus seems way too high to me. I wouldn't go too much higher than the recommended pressures in the car handbook.

I run mine at 30 psi and have no issues with uneven wear.

Both of my cars are rolling on 15's, and shoulder wear is a concern on the fronts, especially on the PA.

The last set of tires on the PA (205/70r15) seemed to favor 40psi as the best balance between ride and wear. Run them at the factory recommended 30-32, and the fronts wear the shoulders fast, but the rears were perfect at that pressure. The new set on the PA (P215/70r15) has a higher load rating, and I think that works in its favor, because the new happy place is 38 psi in the fronts.

I don't have enough data on the Regal just yet (205/70r15), but it seems to be happy with 38 in the fronts as well, despite having torn up a pair of tires within a year with the front due to alignment issues.

I suspect load ratings and tire construction are the biggest factors. The load ratings and tire recommendations were made with the stock tires in mind, which would make sense given the info in the original post. I say just go with what works best. Just keep in mind that overloaded or improperly inflated tires are not happy tires.

My truck has bigish tires on it for a 2wd and its only a single cab short bed. It was with my BFG K/O's that I started to really look at the wear. Without dropping the pressure down pretty low the outer corners wouldn't contact the ground. Since my drag racing days I have always judged tire pressure by contact patch be it right or wrong. When I have the best contact patch is the pressure I generally run.

Now that I've said that look at most lifted trucks and you'll notice that they all wear the middle out of the tires. I attribute that to tires shops over inflating them and people keeping them at that high pressure. I've seen some of my friends trucks have almost full tread at the outside edges of the tires while the middle was down to about 1/8-1/4". I think its a game the tire shops play, fill up his tires and he'll be back for more sooner.

I'll share what I've learned in my years working at a tire shop.

There's a number of different factors that play into tire pressure.

standard load vs extra load, and also the Load index of the tire. there's also LT tires for trucks too with load ranges of C,D, and E but we won't worry about those. Trucks and RWD cars wear tires much differently than FWD cars do. I've noticed RWD vehicles wear out the center of the rear tires and the outside of the front tires. FWD cars just wear down the front tires all over and don't wear the rears down much at all unless you have alignment issues.

In most cases the max pressure of an extra load tire is 51 psi
and standard load max pressure is typically 44 psi

there's also the load index. This is usually a number in the 90's and is found next to the speed rating. Every car has a minimum value for this number for the tire to be able handle the weight of the car. Most tires you find at shops though in the size for the car will work just fine.
Tire shops will calculate the recommended tire pressure based on the gross weight of the car, the load index, and the load range of the tire. I know if you want, you can go to Discount Tire for an air check and you can have them calculate how much pressure the manufacturer believes should be in your tires.

Basically though, the lower the load index (the number) the higher pressure required for your tire to handle the weight of the car.
Also, the higher the load range, the more pressure required for the tire to carry the weight of the car properly.

Ideally, whenever you go to a tire shop and they install a tire with a different load range they will give you a different pressure you should keep your tires at. When I worked at Discount Tire we printed it on the paper work of every sale when tires were bought.

I know GM recommends 30 psi for these cars with factory tires on them. IMO you're just fine going up to 35 psi with standard load tires. If you're using extra load tires you will need a minimum of something like 34 psi depending on the tire.
I don't think there is any danger in going over the recommended air pressure, I don't think it would be wise to go to the max pressure though due to how change in temperature can vary tire pressure.

I run 35 in the Regal with extra load tires.

xxdabroxx wrote:My truck has bigish tires on it for a 2wd and its only a single cab short bed. It was with my BFG K/O's that I started to really look at the wear. Without dropping the pressure down pretty low the outer corners wouldn't contact the ground. Since my drag racing days I have always judged tire pressure by contact patch be it right or wrong. When I have the best contact patch is the pressure I generally run.

Now that I've said that look at most lifted trucks and you'll notice that they all wear the middle out of the tires. I attribute that to tires shops over inflating them and people keeping them at that high pressure. I've seen some of my friends trucks have almost full tread at the outside edges of the tires while the middle was down to about 1/8-1/4". I think its a game the tire shops play, fill up his tires and he'll be back for more sooner.

In my experience, it's always been the guy in the truck who wants his tires inflated more than what the manufacturer calls for. Nearly every guy I've seen who watched me work on his truck believes his tires need to be set at the maximum psi no matter what. Of course the customer is always right. What in the world would I know about tires???
Also consider that most lifted trucks will have larger tires than OEM with a higher load index and load range serving no functional purpose at all. This means you have owners seeing 80 psi as the max pressure on their lifted 1500 truck and proceeding to inflate their tires to 80 psi when it should be something like 50 psi.
I'd venture to guess though that the real issue there is that they're not getting their tires rotated as often as they should be.
As I said above, RWD vehicles wear out the center of the rear tires and the outside of the front tires.

One thing with the trucks, is it on a "1/2" rim? By this, I mean (and GM is notorious for doing this on HD trucks), it's 16 x 6.5 rim, being a little bit narrower for load capacity (hence why many HD trucks are load range E tires to begin with). Anyway, the stock size which is usually around a 245/75-16 from memory, tends to wear fine at the recommended pressure. However, many people (Myself included when I had my 2500HD), hate the scrawny tire look of the stockers, then oversize it. I think I ended up with an LT285 series tire. This tire on a 6.5" width rim, will now cause the tire to "crown" a little, and as such, wear out the center of the tire quicker than the edges.

^^^ I'm sure this is also another factor.

An unfounded opinion of mine about tire construction is one of reasons I believe the tires built now need to have higher inflation pressures for the tires to wear more evenly. - BC

Regarding shoulder wear on front tires - in my view how fast you take corners is a significant contributing factor in how quickly your tires wear down. When I was a 'yoof' I used to drive faster than I do now and tended to take corners at higher speeds. Consequently I noticed that I was wearing out the outer shoulders of the tires pretty quick. Also we have a lot of roundabouts/traffic circles in this country, which as we drive on the left we go round clockwise - so guess what? Tire wear was worse on the shoulder of the left hand front tire than it was on the right.

Since I have slowed down a bit and don't push my cars so hard through bends so often I have stopped seeing such shoulder wear on my tires.

35 psi gets me long lasting even wear across the tread. Below that shears the corners off early.
I always stick with 35.