[BTK]

I've seen quite a few posts in the "MRC jacking up" thread about airing up the tires to 40psi for storage. This has me questioning my operating philosophy on tire air pressure. I currently run my tires at 43psi, with the thinking that the recommended pressure of 35 or whatever is for a softer ride, but more pressure = better economy, tread wear, etc. Am I wrong? This is a lesson I learned from my father 30 years ago. "Run tires at the highest pressure you can without affecting tread wear..." Admittedly, he was always a truck guy, so there may be a difference there due to loading, towing, etc. Thoughts?

[Alpha1BC]

43 is way high. For the tires on these cars, I wouldn't recommend running much more than 1 or 2 PSI over the recommended pressure at most. Recommended pressure is not just for softer ride, it impacts how your tires interact with the road and therefore everything about the dynamics behind a moving vehicle.

Higher pressure only gets you better economy because you're reducing the size of the contact patch with the road. While this does mean less torque is needed to turn the tires, it also means you're not going to have as much grip of you need to turn suddenly or stop hard, and this will only be made worse in wet conditions.

Higher pressure also hurts tread wear. The same smaller contact patch from above is also not as good at reacting road loads as the contact patch at the correct pressure would be and in turn gets worn/damaged faster.

I'd suggest dropping back down to the recommended pressure listed on the sticker in the door frame, and if you're getting poor tire wear after that you could get an alignment. If the outsides of the tires are worn more, get the track alignment listed in the track prep performance supplement (can find that on this forum if it didn't come with your car). If the inside is wearing too much or tire wear in general is poor, try to find an alignment shop that will do the standard camber alignment while moving the toe alignment to be closer to the track alignment spec (i.e., closer to 0 total toe).

Keep in mind that this is a performance car with softer tires than most, so don't be surprised if the tires look more worn than a family sedan's tires after 20k miles. There are other all season tires with better treadwear ratings available as well if you're not keen on the lower treadwear rating of the OEM tires.

[VinnAY]

"Without affecting treadwear" would mean 32psi cold. Like the door jamb tells you too. 43psi is ridiculously high and WILL affect treadwear.

[nelsont]

Originally Posted by BTK

I've seen quite a few posts in the "MRC jacking up" thread about airing up the tires to 40psi for storage. This has me questioning my operating philosophy on tire air pressure. I currently run my tires at 43psi, with the thinking that the recommended pressure of 35 or whatever is for a softer ride, but more pressure = better economy, tread wear, etc. Am I wrong? This is a lesson I learned from my father 30 years ago. "Run tires at the highest pressure you can without affecting tread wear..." Admittedly, he was always a truck guy, so there may be a difference there due to loading, towing, etc. Thoughts?

Ya the engineers don't know a thing- why would you want the car to ride like a buck Board?

Follow Mfg. recommendations.

Tim

[BTK]

Thanks for the good explanation Alpha1BC. As I said, I was going off what was taught to me 30 years ago. And yes, he was an "engineers don't know a thing" kinda guy and said that number on the door jamb was so you would have a softer ride, no other reason. I guess my father didn't actually know everything. Go figure.

[VinnAY]

I do remember a time though that it was on the side of the tire like it just said max PSI or something like that, trying to think that far back before there were labels on the door jambs

[ZED SLED]

Originally Posted by BTK

I guess my father didn't actually know everything. Go figure.

Maybe not, but your father-in-law certainly will.
No matter what I tell my wife, she doesn't believe it unless it can be corroborated by either her dad or the internet.

One thing you will never, ever, hear your wife say, "Oh honey, you're so clever. You're much smarter than my father."

[Airfuel]

The ‘19’s call for 35psi as per door jamb.

[DangerZL1]

Wow! You're going to almost think you bought a Cadillac when you take 8 psi out and realize how much better it handles bumps. If 43 is a cold psi, it probably goes to 45 or more hot.

[nancygrl]

43psi..

[GroundhogSS]

Two over, maybe three at the most.

[nicktechla]

43 cold.. what are they hot? 48? haha, crazy

[TJay74]

Originally Posted by Airfuel

The ‘19’s call for 35psi as per door jamb.

The PSI varies depending on the model, the SS 1LE cars call for 32psi cold. The tire pressure on the tires is the max tire pressure for when the tire is at its max load.

As said, no more than 3psi more than the door jamb is a good rule of thumb.

[BTK]

Originally Posted by DangerZL1

Wow! You're going to almost think you bought a Cadillac when you take 8 psi out and realize how much better it handles bumps. If 43 is a cold psi, it probably goes to 45 or more hot.

Indeed! Old school thinking, performance = hard ride, luxury = soft ride!

Originally Posted by VinnAY

I do remember a time though that it was on the side of the tire like it just said max PSI or something like that, trying to think that far back before there were labels on the door jambs

This exactly. I've had many cars that did not have any info on the jam, weather it fell off, was painted over, or was never there... These run flats have a max of 50psi. The tires on my 2500HD have a max of 80psi, I run 65 front/60 rear.

The recovering addict in me says ANYTHING less than MAX is NOT GOOD. Obviously not true, but it does affect a lot of my decisions

Thanks for the info everyone. I'll be airing down today .