BMW tire pressure study/analysis?

[Russell]

Does anyone know of a definitive study/analysis of the effect of tire pressure changes on BMW handling? I am particularly interested in how tire pressure changes affect stock suspension with stock wheels and tires. Unfortunately, the archives have been of limited help. TIA

[Tiger]

If you pump all 4 tires the same pressure, you will get understeer and car does not turn quickly. If you pump the front tires 4PSI lower than rear, then you will have sharp steering response.

[BMWCCA1]

If you pump all 4 tires the same pressure, you will get understeer and car does not turn quickly. If you pump the front tires 4PSI lower than rear, then you will have sharp steering response.Actually, conventional wisdom says decreasing tire pressure at the front relative to the rear will increase under-steer, and vice-verse: Refer to this tire pressure handling chart (http://209.85.165.104/search?q=cache:8PQ2vVrbR94J:www.kormanfastbmw.com/thandling.htm+%22tire+pressure%22+handling+chart&hl=en&gl=us&ct=clnk&cd=1&client=firefox-a). I guess it all depends on what you mean by "sharp steering response".

[Tiger]

Mmm... strange... by lowering pressure, you should have more traction... so with front more grabby than rear... how is that understeer? Is it the rear tire understeer so that the front controls more?

And if you lower the rear tire presure... the rear wheel will steer the car more... thus oversteer?

[nixter]

I run 41/38 psi and if it dips even a bit I notice it right away. My handling gets VERY jumpy. I have to constantly over correct just to keep the car in a straight line! Reminds me of TV shows where the driver is constantly moving the wheel back and forth. I think that comes from the old days before radials.