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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Wheels and Tires Forum Sponsored by The Tire Rack > Tire Pressure



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      04-14-2008, 11:21 PM   #1
MTV
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Tire Pressure

I'm running a P215/45ZR17 tire and currently have the PSI set at 32 all around. After some mild research I have come to the understanding that higher pressure in the front and lower in the rear will reduce understeer and increase oversteer. Lower in the front and higher in the rear will induce the opposite...

So I'm thinking of running 36 in the front and 34 in the rear. It's in terms of a handling basis, I don't care about the tread wearing faster in the middle.

Any insight?
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      04-14-2008, 11:55 PM   #2
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For a street car, unless you've got some experience, I wouldn't recommend doing anything to promote oversteer as it's more difficult to control for the average driver.
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      04-15-2008, 01:15 AM   #3
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The concept is correct. But on a front wheel drive car (most), I would recommend the same pressure all around to retain chassis balance.

If, however, you want to try altering the pressure levels, I'd suggest 32(F) and 30(R). More pressure causes greatere tire stiffness, therefore less traction.
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      04-15-2008, 12:20 PM   #4
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I put them at 36 PSI all around. Handling is better and the steering response is as well.
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      04-15-2008, 03:11 PM   #5
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i think you got it backwards. like ray said, more pressure = less traction.

to induce oversteer, you want less traction on the rear wheels. so more pressure in the back, less in the front.

to induce understeer, you want less traction in the front, so put more pressure up there and less in the back.

but if you want some understeer, you can just squeeze the throttle with traction control off so you can get the wheels to break loose under the power. that's the greatness of having a RWD drive car. none of the heavy breaking through the turn crap you'd have to do with a FWD car.

practice on a closed track. it's fun. do you guys get this annoying beep beep beep beep beep when you start to lose traction?
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      04-15-2008, 06:16 PM   #6
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...do you guys get this annoying beep beep beep beep beep when you start to lose traction?
nothing audible except for tire noise, but we have a flashing light in the gauge cluster.
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      04-15-2008, 07:48 PM   #7
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Quote:
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nothing audible except for tire noise, but we have a flashing light in the gauge cluster.
that is just DSC at work
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      04-15-2008, 07:55 PM   #8
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Quote:
Originally Posted by Ray View Post
The concept is correct. But on a front wheel drive car (most), I would recommend the same pressure all around to retain chassis balance.

If, however, you want to try altering the pressure levels, I'd suggest 32(F) and 30(R). More pressure causes greatere tire stiffness, therefore less traction.

Ray that's a badass sig you got there!!
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