Factory tire diameter is ~27" so you want to be as close as possible. I ended up swapping my 285-35s to the front since they fit and are the same diameter. For drag racing you'd want a much narrower tire so maybe stick with 245-40s but keep in mind, it will effect your everyday handling due to increased understeer with all that width out back. Your spacers reduce the neg offset of the stock sport wheels. I used this calculator which you can use to determine the difference from your present setup to proposed to make sure it will fit before you buy:
Custom rims, wheel tire packages for your ride - RIMSnTIRES.com
Greensboro here.
Good luck!