Quote:
Originally Posted by Lotus7
You might try going with BMW's recommendation of always maintaining a Rear to Front bias of 3 psi (or more under high-load conditions). Running the front's at 34 and the rears at 37 seems to work well on my 35i using the "Normal" suspension setting. the higher rear pressure reduces the rear slip angle a little under hard cornering, but will have minimal effect of the wind deflection "feel" which is more influenced by tread design, toe-in settings and front suspension bushing compliance than tire diameter (and sidewall aspect ratio). Tiny changes of toe-in can have a dramatic effect on the "self-centering" feel on most vehicles, however it opens a "can of worms" when you consider things like stability control programming, tire wear and rolling resistance.
Many new cars are being set up with low rolling resistance tires (including the X3) and are being aligned with minimal toe-in for the lowest possible drag to enhance mileage ratings. The downside can be slightly less self centering and more wind deflection.
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That’s interesting.
I have front to rear set the same per the door sticker. Going from the recommended 32psi to 35psi did have a positive effect (imo), so I may try a couple of pounds of differential to see how that impacts handling and feel.
Note: even though I’m looking to tweak things a bit, the current ride / handling is quite acceptable. The old X3 was MUCH stiffer and was better in cross winds, but suffered in the ride comfort category.
Next would come the topic of tires. The Bridgestone Dueler’s are rated very low by tire rack. There are few choices in run-flats in the 248/55-17 size but more options in the 245/50-18 size.