Proper tire pressure

[bichmgnt]

I just put new rims and tires on my car and need to know what the right tire pressure is for them.

Rims 17x7.5
Tires 215/40ZR17

I have a 91 325i Cabriolet. The original tire pressure was 29 front/31 rear.

Any good guesses what the ideal tire pressure should be?

Steve

 

[mikev]

call the tire manufacturer or shop tell them the weight of your car then they can advise you on the correct pressure

 

[Wadula]

or just check your fuel cap, or maybe the door sills....could also be in the manual. there is a little table showing the pressures for several sizes. maybe yours is within.

 

[bichmgnt]

There ain't nothin even close in the manual. Everything is for 14 and 15 inch rims.

Steve

 

[Ryan Stewart]

you can still run 30lbs cold for hte street. The sidewalls are thicker so its not like they need the extra support.

On the street I run a 32/34 cold setup and on the track I run a bit higher....

 

[rjp325i]

You should be fine with 30 - 33 lbs for the street. Try different combos and see what you like best. For a driving school you will need more than what you use for the street. Try contacting the Tire Rack, they should be able to help.

 

[bichmgnt]

A driving instructor on another site said I should run no more than two pounds more than the original tire pressure. This made sense to me and I think that's what I'll go with. It's also right in line with most of the reccomendations here.

Thanks guys.

Steve

 

[rjp325i]

Remember the load you carry in the car calls for different pressures. My '89 325i door jam sticker says 32 lbs front and rear for light/normal load and 33 frt and 41 rear for max load. Try a couple different combos. See what works best for the street for you and use it. I like and use 33 lbs all around for the street.

 

[bichmgnt]

I'm finding that all the models are a little bit different. My 91 325iC is 29 front and 32 rear. Basically I'm gonna run 31 front and 34 rear and see how that goes.

Steve

 

[rjp325i]

Your driving style and handling preference will determine what works best for you. A slightly lower (a pound or so) air pressure than your starting point in the rear will lessen understeer if you desire. Try different combos and use a quality air pressure gauge. I have found a digital gauge (Accutire) works best for this purpose.