Engine/Transmission (1998.5 - 2002) SMARTY and Tire Size Question

[Mundgyver]

My thinking is that depending on brand of tire and the style and size the problem will be a varying one. Manufactures all have some very slight differences, tire diameter being one of them. 5 mph is just an example that I used for the explanation. I actually have 3 speedometers that I can look at in the truck. Dashboard readout, Roadrelay, and GPS. When I travel, I drive by the GPS speedometer. Be that as it may, the point of all this, is that the tire starts out at one diameter showing a given speed on the dash readout and as the tires wears, even though the dash readout still shows a constant speed, you are infact slowing down your speed as the tire gets older. Not much, but still some.