I have an extra set of 245/40/17 Hoosier A7's I was using for autoX on my other car but unfortunately won't be able to use them anymore because I'm going to brakes that will require 18's. If I get some 17x9 5x112 wheels can I make them work on my MCS? Or is this a horrible idea? Suspension would be KW with camber plates.

 

We did 225 A7s on 17x7.5+45
the killer was the offset, we needed 20mm or 30 mm spacers iirc to clear the kw clubsports with how wide A7s run, those 17x9s will need to be negative offset if I'm thinking about this correctly. They also stuck out noticeably past the fenders, the Clubsport springs were waaay too soft even for 200tw tires and we had trouble getting the ride height high enough until we put some good Eibach springs on them, I believe we were up to 500#ish by the time the A7s went on and that was working decent enough. Softer and I'd expect you'd have rubbing issues all the time now that the tires are capable of pulling like 1.5g

With 17x9s and the offset needed to clear the strut I'm concerned that the steering will be limited, if you turn too far the tire may rub on the front/rear of the fender arch. There's also scrub radius to consider when pushing the front tires out wider and wider, we struggled a bit with the handling and never nailed down if this was an issue we were having or not.

tl;dr probably if you can slap on some 50mm spacers and get the KWs stiff enough

 

Thanks for the reply. This confirms my suspicions that it won't be worth it to try and make them fit.