Square fitment for 2018 M4...

[Eric Strauss]

For a host of reasons, including canyon carving in relatively remote locations, I am looking to set up a square fitment on my M4 so that a full size spare can fit all-around. Also, I go through 2-3 sets of tires/year and the savings will pay for the wheels by year 2, and 18" wheels weigh less, reducing the unsprung weight. So, I contacted turner Motorsports and they suggest an 18x10 Apex Arc-8 with 275/35-18 all around and have done so with only fresh alignment - no fender rolling, etc.

This is a lease so will go back in 34 months with the 20" wheels back in place.

Does anyone have experience with this fitment? Pictures perhaps?

Thanks so much. I am recent convert from Audi (last nine cars have been Quattro - mostly S4, S5, RS5), but I no longer live in New England so can now rejoin the rear-drive club.

Thanks and Happy Motoring

Eric

[TostitoBandito]

Probably not gonna find many M4 owners on here, but it should be pretty straightforward if you know the offset of the stock wheels and the offset of the arc-8's you want. You'll want to measure clearance from tire to fender lip and from tire to strut both front and rear. After that, it's just some math to plug in the new wheel and tire sizes. You may need spacers depending on the offset of your wheels.

You'll also want to be mindful of tire height if you're going to a smaller wheel. You'll either need to compensate with a higher aspect ratio (thicker sidewall) tire so that your 18's with tires are close to the same height as your 20's with tires, unless the M4 has adjustable ride height stock (which I doubt). You'll mess up both your speedometer readings and ride height if you make a significant change in total wheel height.

And I'd believe Turner since they've likely put that exact configuration on an M4 before. Also, if you email or PM the guys at Apex they can be very helpful since they're experts on how their wheels fit on basically any modern BMW. I think they're on Instagram as well, with galleries show their wheels on many BMW models.

[Eric Strauss]

Thanks so much... still a newbie on this site. I am a Senior Member on the AudiWorld site. Great idea to contact Apex...

Best wishes
Eric

[TostitoBandito]

Yeah definitely hit up Apex. They're active in this forum and they helped me as well when I was deciding what tires to put on my ARC-8's (and what color to get). My best info came from them. They know all the common fitments and can tell you exactly which wheels and tires you can use.