We changed out the stock wheels/tires on my wifes TB to 275/45R20s a week ago. According to a couple of tire size calculators the new combo is somewhat larger diameter than the stock setup. "Should" see a 3 to 4 mph difference at 70 mph. Finally got out on the highway yesterday with the GPS so I could tell her how much slower to drive to be safely at the speed limit. Was very surprised to find the speedo speed matches GPS speed EXACTLY at all speeds up to 75. MY GPS doesn't read fractional MPH, but if I set the cruise control at 60 both the speedo and GPS locked on 60 until I changed speed.
Unfortunately I never did a comparison with the stock setup. I just "assumed" the speedo was correct. Nice to know I don't have to pay to have the tire size recalibrated in whatever computer the TB uses for milage.
Alan
Unfortunately I never did a comparison with the stock setup. I just "assumed" the speedo was correct. Nice to know I don't have to pay to have the tire size recalibrated in whatever computer the TB uses for milage.
Alan