Model T Coupe with 302 engine.Question:  Understandably, this is a custom application. I have shoehorned a Hipo 302 with a C4 and narrowed 8" rear into a 1925 Model T Coupe. I am running 10"x15" tires on the rear and 5"x14" up front. Originally the rear had 2.78 gears. I have installed 3.80 with a locker but feel the RPM will be quite high for a comfortable long distance ride and a 12 gallon fuel tank. I am leaning towards either 3.00 or 3.25 rear ration. Any advice?Answer:  Below is a quick formula that will let you calculate te correct gear ratio that you need.RPM= MPH x  Gear Ratio x  336   then divide this by tire diameter in inches. This will tell you what RPM you would be at with whatever MPH & Ratio you select.Give Lance or James a call toll free 800-444-0755 the can help you get the correct parts the first time.