Tire Pressure Question, Yes I have searched :)

[ATF]

Hey guys, I was taking a look at my door jam and noticed that my tires don't match any of the recommended tires/pressures on the chart.

The PO put P205/65R15 92T on all 4's. I've been guessing that 29 in front and 32 in the rear was a safe bet, since the chart in the door jam showed those pressures for slightly different tires. After doing some searching here on the boards, you're looking at a +/-6 PSI margin in terms of control, safety and tread wear. So is it safe to say I can just inflate these bad boys to 32 all around?

I don't want to hurt myself or others by under/over inflating the tires, so rather than guessing I'm right, I wanted to double check with you all.

Thanks,
Nick

[clex2]

ATF,

Tire pressures are like oil brands. Ask and you'll get different answers. In general, car companies reccomend lower pressures for the front tires for safety reasons. Usually, the lower the pressure, the less resoponsive the tire is, which can mean less grip too. The car will tend to understeer. Now the higher the pressure, the less rolling resistance there is, so in theory you'll get better gas mileage. However, the ride will be harsher and the car will be more responsive.

The ideal tire pressure is tailored to what you want your car to do. Do you want a smoother ride....less pressure. Are you tracking your car? If so, the ideal track pressure will give the tire the same tire temperature across it's width. Hardcore track junkies use infrared tire pyrometers to measure the tread temperatures. When it's the same from the inside to the outside of the tire after taking a few hot laps, they've got the right tire pressure.

For my daily 318ti, I run 35-36 psi all around.

[Jean H.318TI]

i run 45psi all around

[96cali]

I ran like 32 then switched to 38 all around and like it better.

[machinesteve]

38 all round is good.

[jggonzalez]

Do you get uneven wear at those pressures? I was running 36 psi front/32 psi rear and my rear tires got a stripe down the center of hard wear and just light wear at the edges.

[machinesteve]

They seem to be OK. I started with what you have and going to an even number all round transformed the car. I have the M-Power version so the tyres may be different (fatter). But whatever you do ignore the BMW book figures.