I have a speedometer question. I know when using bigger than stock tires it throws off the speedometer. I saw a show, maybe Stacey David's Gears, where he mentioned a company that, if you told them what size tires you were using, they would adjust a speedometer that would give the correct speed. Anyone aware of such a company? Or a formula to calculate the speed according to the tire size? If this is the wrong forum, let me know. Thanks.