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[Mvez]

Hi guys, my GT3RS has been retired from track duty, and I will soon be starting an E92 M3 track build. I want to run a square BBS E88 setup for the track. The fairly well known size of 18 x 10 ET25 seems to work well for 275-35-18.

I plan to use that size up front, but has anybody tried 275-40-18 in rear on the ET25 ? I assume it has plenty of room and won't rub.

Also, can anybody confirm that the this wheel size for the E88 will clear a 370-380mm BBK ? I know the Schirmer M3's run a 10" front E88, but I don't know the offset.

Help is greatly appreciated guys.

[AP3X_FTW]

As a guy who owned/tracked an e46 M3 and GT3, some of this may be review for you.

You do not want to run 275/40/18's in the rear, as this is too tall and will throw off the overall rolling diameter. Furthermore, one of the biggest benefits of running a square setup is to gain the ability to rotate tires effectively.

The most common square setup for the track is 18x10 et25 as you mentioned. This will allow you to run 275/35/18 extreme summer tires, or r-compounds depending on your experience level. Some coilovers like KW clubsports will require you to run 5mm spacers up front to avoid rubbing the spring perch. The 10" wheel is more than enough width for 275 extreme summer tires.

Some drivers using r-compunds choose to run 18x10.5 et27 square, as the 10.5 wheel provides more sidewall support. R-compounds run wider than your average street/extreme summer tire, therefor the 10.5 may be warranted. Another popular tire configuration with 10.5 square would be 285/30/18's.

Last, some drivers just prefer a staggered setup. There are a few iterations depending on how much tire you want to run.

F. 9.5 et22 - 265/35/18
R. 10.5 et27 - 285/35/18

F. 10 et25 - 275/35/18
R. 10.5 et27 - 285/35/18

F. 18x10 et25 - 275/35/18
R. 18x11 et - 295/35/18

I answered your question back in the Schirmer thread, but here are the specs on that car again.

Wheels:
BBS E88
F. 18x10 265/35/18
R. 18x11 295/30/18

Tires:
I have seen them use Toyo R888, Yoko A048, Michelin PSS Cup, Dunlop Star Spec's etc.

Suspension:
Custom Schirmer 3-way suspension w/ modified axle kinematics

Brakes:
AP Racing BBK
F: 6 piston 378mm
R: 4 piston 356mm

Etc.
Lots of GT4 bits
Weight 3,220 lbs

The boys on the other side of the pond tend to gravitate towards a staggered setup for the E9X chassis, and I am not sure exactly why that is. Maybe this is favorable for the Ring? They also love there Michelin PSS Cup tires, but the limited size offering can be tough to work with.

[JEllis]

One more staggered setup.

This is what I am running

F: 9.5 x 18 ET19 275/35/18 RS3s
R: 10.5 x 18 ET19 285/35/18 RS3s