# Tire pressures

What is the mist optimal tire pressure for around 15 to 20 celcius.

What tires? 20 char…

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Need info on Tires and class. One rule of thumb you can use is to have hot pressures not read more than two psi above cold.

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Its j125 X30 and i have a medium conpound

What brand of tire is it and what is the compound called? Usually they are named by a color or letter designation.

There are dozens of tires that could be called a “medium compound”.

The color is yellow and its a mg tire

MG Yellows your cold pressure should be between 7.5 psi - 9.5 psi depending on track conditions. Lower if it’s hotter, higher if it’s colder.

We typically stay around 8 - 9 for most conditions. Lower than 8 or higher than 9 would be for fairly extreme track conditions.

For the sake of complete info for new guy, define what Hot and Cold is, maybe.

Odd factoid: my summer pzeros have a very definite “cold” point. At 45 deg F, they start doing the “acorn” noise when turning wheel parked. This is when you know you have to be careful, really careful.

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Cold = before the session
Hot = after the session

Set your pressures before the tire is warmed up, check them after the session. You’ll want 2-3 psi of pressure increase usually, maybe more or less if you’re running nitrogen vs. air.

I mean ambient. If I read you correctly, if it’s hotter than X you deflate a bit, if it’s colder than Y, you increase pressure.

In general what’s considered “normal” operating ambient? 60-90f?

I think that’s overthinking it too much. You have a range of ambient temps you normally race in and a range of pressures to use. Fairly simple, use the higher pressure when it’s colder out, use the lower pressure when it’s hot out.

We’re talking a range of 2 psi, pretty hard to screw it up too badly.

Yeah I guess so. He can always ask around for general pressure range at his track.