[LurkingBimmer55]

Hey F87 Gang, I've purchased my first car last spring and have been lurking around here ever since. My current ethos is two reduce weight with forward/rear distribution in mind. I've gone down a few rabbit holes this winter while the car is in storage and if there's any interest in this post I'd be happy to share more.

Semi-important preface, this is a street car but planning modifications to theoretically improve it helps me sleep well at night.

First of all, I looked at reducing rotating mass from the front via wheels/tires/brakes. The obvious answer is too drop down to 18" wheels but I did come across some notable results.

Word is that the Conti SportContact 7s are good but when I did my 'research' I was focused on PS4S.

According to Michelin Canada website and BimmerTips [1] the OEM 437M front wheel + PS4S Star tire weighs 45.71 lbs. Switching to non-star PS4S, the weight drops 0.88 lbs to 44.83. (Perhaps because of different tread depths?)

a. BMW 437M 19", 245, non-star = 44.83 lbs (-0.88)
b. Apex VS5-RS 19", 245, non-star = 41.73 lbs (-3.98)
c. Apex VS5-RS 19", 255, non-star = 42.63 lbs (-3.08)
d. Apex VS5-RS 19", 255, Star = 45.1 lbs (-0.61)
e. Apex VS5-RS 18", 245, non-star = 41.49 lbs (-4.22)
f. Apex VS5-RS 18", 255, non-star = 43.98 lbs (-1.73)

If this post picks up traction I'd be happy to clean up my raw collected data into a more legible format for everyone. I may also look into the rear wheel/tire package too.

TLDR; Dropping to 18" can net us the most weight reduction but sticking with 19" wheels via VS5-RS gets us within a quarter pound (and M2 CS styling.) Most notably, stepping up to 19" VS5-RS with non-star 255 tires (Michelin P/N 66901) is still 3 pounds lighter per front corner than OEM.

*Disclaimer* I am not a financial advisor or have driven my car in any way other than completely stock and relatively safely.

[1] https://bimmertips.com/oem-bmw-f87-m2-wheel-style-specs/

[smmmurf]

Hello, I have switched from steel brakes to ceramic brakes on a different car and the difference was noticeable; the weight savings is about 10 pounds per corner. I then swapped the factory cast wheels for BBS forged wheels for another ~8 pound reduction per corner and the ride was transformed (total 70+ pound rolling mass reduction).

2-3 pounds per corner improvement will be helpful to acceleration, braking, and response but the difference will be hard to feel unless you combine this with more weight reduction besides the wheels.

Interestingly, lighter wheels do not equate to a better ride in all circumstances. I found that that larger bumps are more jarring than before since the heavier wheels had more inertia. Smaller bumps will be better controlled since the suspension has less work to do.

[DanG]

Let us be honest here. Reducing a few pounds per wheel for street use will be totally unnoticed. It probably will reduce lap times on a track.

Stock 437s are pretty light. Much lighter than the 788 on M2Cs. But Michelin PS4Ss are a great improvement over PSSs or Conti 6s.

I bought new wheels because my 437s were peeling. Weight reduction wasn't a factor in my decision but looks were.

A bigger difference in my opinion is added a strut bar. It gets rid of any lean in a corner.

[iWayne]

Originally Posted by DanG

Let us be honest here. Reducing a few pounds per wheel for street use will be totally unnoticed. It probably will reduce lap times on a track.

Stock 437s are pretty light. Much lighter than the 788 on M2Cs. But Michelin PS4Ss are a great improvement over PSSs or Conti 6s.

I bought new wheels because my 437s were peeling. Weight reduction wasn't a factor in my decision but looks were.

A bigger difference in my opinion is added a strut bar. It gets rid of any lean in a corner.

I disagree - reducing rotational weight makes a huge difference. Dropping 4-6 lbs from the stock 19" wheels, I felt a huge difference in steering feel just leaving the shop. Fighting for that last 1-2 lbs may not be worth it for most ppl, myself included but can't fight the laws of physics.

[M Fifty]

I think BeePee switched to even lighter BMW 18s and appropriate tyres, so would be a useful person to ask for street use (even though he does track his car).

[KevinC]

Originally Posted by DanG

Let us be honest here. Reducing a few pounds per wheel for street use will be totally unnoticed. It probably will reduce lap times on a track.

Not my experience at all. When I've reduced unsprung weight on my street cars, even 3-4 pounds is enough to notice IMMEDIATELY. If you can go further, even more drastic improvements.

I put forged 15" BBS wheels at 10.8 lbs on my Scirocco back in the day, a reduction of about 9 lbs over the previous alloys, and that made an unbelievable difference in turn-in, ride quality, and even out-of-the-hole acceleration.

The combination of heavy 788's and the massive steel brakes on the M2c is a heavy affair. I wish the standard brakes offered in other markets would have been standard here. That setup is no slouch (especially for a street car) and significantly lighter.

[cvitt]

Have a look at edelweiss wheels …