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[eljay]

So, I am on the hunt for 270m wheels for my E91 LCI xDrive and I'm almost ready to pull a trigger on a set, but now I have second thoughts on whether it's a good idea.

Please note: this is not a thread about whether wheels will fit or rub or look good!

The wheels in question have an offset of ET20 and I will be mounting 225/40R18 tires on it. So, they will fit under fenders without rolling and rubbing and look good!
But! Compared to my 16x7 ET31 wheels, they will be 23.7mm further out.

My questions are:
Will this put undue stress on wheel bearings?
Will my geometry change significantly?
Will I require different alignment settings?

I really like the 270m wheels and I am looking for an 18" setup with OEM M wheels, so no I'm wondering if I will be fine with these or should I keep looking fir other wheels like the 313m that have offsets closer to factory range.

Thanks.

[cdm244@gmail.com]

Interesting question but I am confused on your math. Consider where the center line of your old vs. new wheel/tire will roll along the ground. Looks like the center line of your new wheel will only be 11mm out from stock - the 31mm minus the 20mm for the new wheels. I think there would be no significant impact at 11mm. You should look up scrub radius as an increase will slightly move steering effort towards the heavier side. By the way I have ARC8's at et40 but with 12mm spacers so my "effective"offset (as opposed to the true offset of the wheel casting) is et28 but since my stock BMW wheel had an et of 34 I'm only out 6mm from stock. I noticed no change in steering effort - but I like the nice heavy feel of the e90 geometry (and incidentally the best result of the Apex wheels is the truly noticeable reduction in unsprung & rotating weight - no offense to BMW but their stock wheels are boat anchors).

[eljay]

Originally Posted by cdm244@gmail.com

Interesting question but I am confused on your math. Consider where the center line of your old vs. new wheel/tire will roll along the ground. Looks like the center line of your new wheel will only be 11mm out from stock - the 31mm minus the 20mm for the new wheels. I think there would be no significant impact at 11mm. You should look up scrub radius as an increase will slightly move steering effort towards the heavier side. By the way I have ARC8's at et40 but with 12mm spacers so my "effective"offset (as opposed to the true offset of the wheel casting) is et28 but since my stock BMW wheel had an et of 34 I'm only out 6mm from stock. I noticed no change in steering effort - but I like the nice heavy feel of the e90 geometry (and incidentally the best result of the Apex wheels is the truly noticeable reduction in unsprung & rotating weight - no offense to BMW but their stock wheels are boat anchors).

Thanks!

Ah, yes, what I stated was where the outside of the wheel will be in relation to my current wheels. But, you are correct that the center line is what is important to bearing load and geometry and that will only be 11mm out. I think I should be OK with my driving style and mileage I put on the car. I just didn't want to make things significantly worse.

It's interesting how tiny differences like that make a difference in a handling package. For example, there are regular E60 M wheels with offset of ET20 and the same version of that wheel for E60 M5 has ET14.

Thanks for the response and setting things straight.