...that calculates at X mph how far off your speedometer is with different size tires. i remember seeing one it seems like it was a tire place like
www.tires.com or something. when you punched in the tire size you want versus the stock ones, you can enter a mph and it will tell you how far off you are. can anyone help out? its actually for my father, he put 31" (31x10.5x15) tires on his f-150.
