Need offset advice for winter rims

[nj325ci]

I'm preparing to get snow tires on dedicated rims for my 2016 228 Msport with track handling pkg. Think M235i as the M brakes and wheels are the same. I have a set of the base 17" wheels from an F30 that clear the calipers and appear to fit well with no rubbing anywhere but the offset is different. Here are the specs:

Stock wheel - style 461m- 7.5x 18 ET 45 front, 8x18 ET52 rear
F30 wheel- style 393- 7.5x17 ET 37

The F30 rims sit within the wheel wells but are closer to the edge of the wheel well than the stocks. Am I running the risk of suspension or other damage running these rims with the 17" (minus 1?) equivalent tire for the winter?

Thanks very much, Bill

[afadeev]

I'm preparing to get snow tires on dedicated rims for my 2016 228 Msport with track handling pkg. Think M235i as the M brakes and wheels are the same. I have a set of the base 17" wheels from an F30 that clear the calipers and appear to fit well with no rubbing anywhere but the offset is different. Here are the specs:

Stock wheel - style 461m- 7.5x 18 ET 45 front, 8x18 ET52 rear
F30 wheel- style 393- 7.5x17 ET 37

The F30 rims sit within the wheel wells but are closer to the edge of the wheel well than the stocks. Am I running the risk of suspension or other damage running these rims with the 17" (minus 1?) equivalent tire for the winter?

Thanks very much, Bill

Bill,
You will be perfectly fine.
The 228 is engineered to run with either 17" or 18" wheels, and your offset differences are relatively small.
Front and rear tire clearances will be fine as well, especially if you go with narrower winter tires. See below.

For the fronts (stock 225/40R18, IIRC), the outside wheel lip is only 8mm pushed further away from the vehicle center-line. To make winter tires work best, you would want to go with the narrower tires, so something like 205/50R17 (identical rolling diamter). These will be 20mm narrower (10mm on each side), so the net result is that the outer tire sidewall will be 2mm closer inboard vs. stock on the outside of the wheel - virtually indistinguishable.

To visualize, look at the picture diagram of stock vs. new here: http://www.willtheyfit.com/index.php?wi ... offset2=37

For the rears (stock 245/35R18, IIRC), the outside wheel lip is 8.7mm pushed further out. Again, very small delta, that will be similarly negated by mounting narrower winter tires. The rolling diameter of 205/50R17 winter tires (plenty to choose from at tirerack.com) will be -1.27% smaller, so at 60 mph your speedometer will read 59.24mph. But that is also well within normal range of tire circumference variance as you go from full to near worn-off tread (12/32 full - 2/32 bold = 8 mm).

http://www.willtheyfit.com/index.php?wi ... 7#isPage=1

Both front and rear inner wheel lips will be further away from the strut, but that will not harm anything.

a

[nj325ci]

Thanks so much for the detailed response! That's a great site and the illustration is very helpful.

Bill