Recommended tire pressure

[Nicky7]

Hey guys,


I know the recommended tire pressure is 35 PSI. I also know that anything from 30 to 36 is considered acceptable.


I am finding that when I start my car & when it's cold, the tire pressure is reading 28-29 PSI via my diagnostics, but later in the drive, it increases to 31-32. Looks like there is a solid difference between hot and cold.



When the tires are hot (i.e. I've been driving for a good half hour to an hour), is this the point I should aim for the 35? I think this would be the way to go, as the PSI would sink to 33ish when cold?



Anyone else experiencing the same thing, and is this a logical conclusion?


Nick

[ZDan]

Recommended pressures are cold. IMO 32-35 psi cold is fine for street.

[NoHaveMSG]

It says "Cold Tire Pressure" on the sticker inside the driver side door jam.

[Nicky7]

Thanks guys. Appreciate the info...

[Capt Spaulding]

Tire pressure isn’t the end in itself. It’s a path to tire temperature. Lower pressures lead to more tire flex and higher temperatures. I wouldn’t spend a lot of time chasing hot a specific hot pressure. For normal street driving use the cold pressure the oem advises unless you have a good reason not to. For tracking get and learn to use a pyrometer.

[cmiovino]

You're thinking about it too much. Tire pressures changed based on temperature. If you drive, they warm up. In excessive cases like track or autocross, you can set them at X PSI to start and even after a 45 second autox run they can be up 2-3PSI. That and with every 10 degrees of ambient temp, pressures change by about 1 PSI. So if you leave your house in the morning for work at exactly 35 PSI when it's 40 degrees and it's 70 later in the day, even without driving heat factored in, you're looking at about 38 PSI 'cold' pressures. Add in driving and you might be up around 39-40 even.


Bottom line, pressures change. It doesn't need to be exact. Manufactures set a pressure on the door to get you in the right range with those OEM tires. The minute you swap tires, the door pressures go out the window.


A lot comes down to preference too. I prefer setting even the OEM tires to 36-37 when it's about 70 degrees out to account for lower ambient temps they might be seeing down to 50 so I'm not going down past 35 PSI. If they're at 40, it's also not a huge deal. Just me though.