Re: 65 Mustang Coup wheel and tire help needed please.
To keep tire height inline with the wheel wells, you're probably looking at a 225/45-17's. The key to how it effect the mileage lies more in the total height or diameter of the tire over the size of the rim. Your bigger problem may be your lugs. If you have the 4 bolt rim, there's not much out there and you'll have to make the switch to a 5 bolt, with those, Discount Tire may have something you like.
'Scuse me, while I scrape this Honda outta my treads.