I've mounted my wheels up finally w/275/35/18s RT-615s, and no problems on the street. But with a stock suspension, not after market like you have, are you confident there will not be rubbing interference on the fender under track cornering conditions?
I'm a bit worried for my 1st event next week as they sure look close to, or even slightly beyond the front fender edge
Also what tire pressure do you recommend on track with these? With 235s RT-615s on stock wheels I was running 38 cold, but am thinking less for these?? Not really sure.