I have been considering putting a supercharger on my 2012 e93 M3 and am concerned that my competition wheels with 265/35/19 tires in the rear will not be sufficient rubber. I'm assuming that if I want to run 305s in the rear and 285s in the front, I'll have to widen the front fenders. I really don't want to go the wide body kit route because all of the ones that I can afford are fiber glass, I can't roll the fenders because they're plastic and I don't want to take the fender liner out because my car isn't driven solely on the track. Of course, there's the option of not super charging the car but that would be the reasonable thing to do and if I was reasonable, then I would be driving a Prius and not posting this thread... I'm wondering if anyone knows of another option, whereby I can modify my front fenders to accommodate a much larger tire. Appreciate the feedback in advance.
The Apex Wheels folks have a lot of BMW-specific fitment experience, they might be good to ask the widest tires that can be run on a E92 M3 without modification, & see how close that gets you. Plastic welding is often a part of modern bodywork repair, maybe a good body shop that does plastic welding could re-shape the stock front fenders. I wouldn't be surprised if that would require repainting the fenders though.
Thank you very much for getting back to me. The guys at Apex were very helpful; based on their recommendation, I am planning to run 285/30/19 Toyo R888R all the way around on the track. They didn't seem to think I would have any issues with tire rub if I adjust my coil overs back to stock height . The only way I'm going to know for sure is when I'm on the track in a few weeks. I talked with one of the guys at ModBargains who is a regular track driver with the same e92 M3 with an ESS VT-625. He told me that he is running 305 rears with 285 fronts, without any modification to the stock e92 M3 body...wow! For wheels, he suggested Forge Star 19x10 fronts and 19x11 rears; the same setup as his car. I really like my BMW competition wheels but I'm going to have to go with a bigger wheel like the Forge Star CF5V which is comparable looking. Of course the simple thing to do here is to no super charge the car...yeah right, ha!
Personally, I'm a fan of square setups, especially for track events - you can swap the tires around as needed to even out wear, & a square setup should allow for a relatively neutral handling balance. I could see high hp possibly needing bigger rear tires, although keeping all inputs smooth including throttle input (vs. wheelspin-inducing throttle-stabs) possibly helps. I don't have have experience w/ heavily boosted/high hp, although I would imagine proper & well-implemented tuning to manage how the power comes on would help to keep things manageable. Usually F1 or Indy cars are the ones that have enough hp that wheelspin could be induced in almost any gear at almost any speed (in dry conditions, that is) - otherwise, the bottom of the friction circle is pretty flat for the bulk of us not rolling around on racetracks. Oh ya, forgot - R-comp widths may be.. conservative - the manufacturers sometimes stretch that envelope a bit.
