Originally Posted By: steve20
if the new wheels are of a different diameter-you are getting the same MPG as before--the speedometer/odometer is off, so you may be unintentionally speeding...............
If you ahve a GPS with spped rating check your speedo against the GPS reading
Oh yes, I include that in my MPG calculations. For the tire size change, I cover more distance per rotation. After 300 miles, I can add an additional six miles from what my OD says.
On stock tires, when my speedometer would say 65 for example, GPS and road-side radar would tell me 1mph lower. With the new tires, its usually exactly the same, sometimes the speedo reading 1mph less. I should track the ODO exactly with my GPS and see what results of it. Is a GPS *that* accurate though over large distances?
if the new wheels are of a different diameter-you are getting the same MPG as before--the speedometer/odometer is off, so you may be unintentionally speeding...............
If you ahve a GPS with spped rating check your speedo against the GPS reading
Oh yes, I include that in my MPG calculations. For the tire size change, I cover more distance per rotation. After 300 miles, I can add an additional six miles from what my OD says.
On stock tires, when my speedometer would say 65 for example, GPS and road-side radar would tell me 1mph lower. With the new tires, its usually exactly the same, sometimes the speedo reading 1mph less. I should track the ODO exactly with my GPS and see what results of it. Is a GPS *that* accurate though over large distances?