Quote:
Originally Posted by x233
Pretty sure they thought something into it. Must be well within the limits of how the car's all wheel drive is calibrated. I am an xDrive guy and I use 220/40 front and 255/35 rear which seems closer to that ideal you mentioned and it seems to work fine so far, in fact I like how the car handles that way.
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I agree that it must be ok if it can be spec'd that way from the factory. I have the stock OEM staggered PSS for my summer setup. I also have 225/40 front and 255/35 rear for my winter set and agree that it seems to handle better. They are mounted to wider wheels so I don't know if the improvement is in the wider footprint of that xDrive functions better with equal diameters.
I theorize that the stock smaller diameter rear tire is read by xDrive as slipping sooner than it should and power is shuffled to the front. With the equal front/rear diameter and a wider rear, the car feels more rear wheel planted and less likely to shuffle power to the front. I actually feel like there is less understeer with the more staggered but equal diameter setup, which I was concerned about because in theory there should be more understeer.