It can certainly be done, but it is not a bolt-on fitment. It requires the right recipe of wheel specs, tire size, negative camber, spring configuration, etc.
For most enthusiasts, 18x10" ET25 front, 18x11" ET44 rear staggered fitment is most effective for both street and track duty. Pair these with 275/35-18 tires up front and 305-35-18 tires in the rear respectively (or a few other common tire configurations) and you have a great bolt-on fitment. With that said, many of our clients are serious track nuts, participate in time attack events, or compete W2W. Not only are they looking to maximize grip, but many desire a square fitment for a well balanced chassis with the ability to rotate wheels and tires on all four corners.
In order rotate effectively, the wheel specifications needed to be cohesive from front to rear. This means that either the front or rear will need some level of "work" to properly fit an 11" square fitment.
Option 1: Front & Rear: 18x11 ET44
Commonly paired with 295/30-18 or 305/645-18 tires
The 18x11" ET44 was specifically designed for the rear of the F8X chassis, so naturally this is a direct fit out back. When we install these up front however, thick spacers are required for proper strut clearance. Breizh Motorsport's (
more photos) chose to go this route, and installed 25mm spacers to clear their KW Competition suspension. Keep in mind, spacer thickness will depend on the front tire brand and suspension type, as not all are created equal. An 11" ET44 wheel paired with a 25mm spacer gives us an effective offset of ET19, so this ends up being quite an aggressive fitment on the outside/fender side and a healthy amount of negative camber will be required to bring the top of the tire in under the front fenders. Since you will (should) only find this type of fitment in the hands of racers, aggressive negative camber specs are par for the course and not a limiting factor.
Option 2: Front & Rear: 18x11 ET25
Commonly paired with 295/30-18 or 305/645-18 tires
The 18x11" ET25 was specifically designed for the rear of the E9X M3, and in this scenario it is better suited for front end as the lower offset lends itself to more inner strut clearance. Naturally, this transfers the focus to the rear of the car, where the 18x11" ET25 is very aggressive (28mm more aggressive then the factory 19x10" ET40 rear wheels). In effort for these to work when the car is put through its paces on the race track, rear fender modifications will likely need to be performed in the form of "pulling/re-shaping" in combination with additional negative camber. Brett Strom from Strom Motorsports (
more photos) is well versed in this arena and no stranger to modifying factory fenders, therefore he chose to go this route. In some cases we have reports of customers using this square fitment with 305 tires without needing to modify the rear fenders, however adding -2 degrees or more of camber in the rear was still necessary.
In conclusion, neither of these 11" square fitments are considered "bolt-on fitments" and should only be reserved for serious track/race cars. It is important to note that regardless of which offset you choose to use, compliant track oriented suspension equipped with linear springs and a spring perch location above the front tires will be required to maximize inner clearance to the strut.
--Dylan