here it is tires size how tall they are. and the gear size at 55 what is the rpms. sometime cam book will tell you but i have the formula and the weigh of the car . if light like a 30 ford with a small block in it you need more stall on the trans converter than you think. and to much rear gear will not help. you will have both feet on the brakes and it will chug thru stop lights most of the time a good rv cam is all you need. but who builds stuff like that