one sweet ws6

i was wondering if a 305/45/17 would fit my car i was wanting a wider taller tire for the track and i like thst mickey thompson tire in rhst size. Im getting new rims anyways so am i better to go 18s in the back? Car has 275/40/17 nitto extreme drag radials on the back now and there way to narrow. Im not wanting to do any pounding cutting or anything thanks