Tire pressure

[AF_kiastinger]

I have 8.5 wide wheels in the front and 9.5 in the back. Whats an ideal number to keep my tire pressure at?

 

[hummus]

Best bet is to check the label on the driver door jamb. I usually add ~2 pounds to that to account for temp fluctuations and slight leakage over time, but for all I know the manufacturer already accounted for that.

 

[RM7]

Best bet is to check the label on the driver door jamb. I usually add ~2 pounds to that to account for temp fluctuations and slight leakage over time, but for all I know the manufacturer already accounted for that.

That PSI is usually your "cold" PSI and tires will increase several PSI just from driving and the heat in the day. When we autocross we end up letting a few PSI out after every run, since they will heat up that much just after one. While our targets might be different in that application, I would recommend setting to the cold number on the door IF your tires are cold, say 70 degrees, shade, no driving for a few hours. When it gets real cold, like sub freezing, you should add a few to get you back into the normal range.

 

[nhcowboy28]

I like to use the sidewall PSI listed in the tire… then double it.

 

[hayagix]

There isn't a lot of space between tire and wheel for give. I run 40 lbs.

 

[RM7]

Typically the wider you go, the less you can run, this also has to do with how hard you push the car, but chances are you aren't going to get racing-rollover from most normal driving. 40 sounds a bit high, at least cold. Are we talking 225/255 or something wider? Tire volume plays into it, not just wheel width. 40 is usually on the high side for most performance cars with their wider tires. 30 is usually on the low side, but some go in the low 30s for cold temps. There are some rules of thumb you can use. It's like 1psi per x lbs.

 

[MerlintheMad]

There isn't a lot of space between tire and wheel for give. I run 40 lbs.

I ran recommended psi on my first set, and the outer (especially left) tire edge wore down much faster than the center: the tread was gone on the outer edge while I still had some millimeters to the wear bars in the center. When my wheel/tire guys swap wheels and raise the psi their standard is 40 psi. I've been running 40 psi all around. The rears were recently replaced and the wear was pretty even (the first wear bars to touch were the outer edge of the RR). So far (with c. 4K miles to go) the second set of fronts, run continuously at 40 psi cold, look to be wearing evenly. So, at this point, I think that if you corner aggressively, a higher psi than factory recommended is necessary to prevent premature outer edge wear.

 

[jthrelf]

Whatever the door jam sticker says. I forget - what is it 38/36psi for the Stinger front/back? No issues so far...

 

[RogueIV]

I have 8.5 wide wheels in the front and 9.5 in the back. Whats an ideal number to keep my tire pressure at?

Wheel size isn't the deciding factor, the tire size and load rating is. If you're still using the stock tire sizes use whatever is on the sticker.

 

[Kamauxx]

I have 8.5 wide wheels in the front and 9.5 in the back. Whats an ideal number to keep my tire pressure at?

Find some blacktop and try the chalk test. That's your easiest way to be sure non-OEM tires will wear evenly.

 

[hummus]

I've been running 40 psi all around. The rears were recently replaced and the wear was pretty even (the first wear bars to touch were the outer edge of the RR). So far (with c. 4K miles to go) the second set of fronts, run continuously at 40 psi cold, look to be wearing evenly. So, at this point, I think that if you corner aggressively, a higher psi than factory recommended is necessary to prevent premature outer edge wear.

39-40 cold works for me. I read a rule of thumb somewhere that a 10 deg F drop will lower psi by 1. My observations seem to support this. Even when I fill to 39-40 on cold tires, I still occasionally get a first reading of 38 on the display (and yes, I have checked for agreement between the car's reading and my gauge). And this happens in sunny, temperate South Florida.

 

[MerlintheMad]

39-40 cold works for me. I read a rule of thumb somewhere that a 10 deg F drop will lower psi by 1. My observations seem to support this. Even when I fill to 39-40 on cold tires, I still occasionally get a first reading of 38 on the display (and yes, I have checked for agreement between the car's reading and my gauge). And this happens in sunny, temperate South Florida.

I try to not get OC(D) about this: my handheld tire gauge reads c. 3 psi above the 40 psi that my tire and wheel place inflates to: while the TPMS indicates between one and two psi over the shop 40 psi. Then, when I drive around for a while, I'll check the TMPS and inevitably all four tires will vary from all showing exactly the same psi, to the highest being three or four above the lowest. Strict accuracy is not possible, and neither is consistency.