I have 235/45-17 wheels. I topped out to see how off my speedo was compared to GPS. Speedo read 118. GPS read:



Am I within normal deviation limits?

Jae

 

i know i checked my garmin vs my dash. at 130 it read 126. so i guess im a little closer. so at 120+ its off a little under 4 mph.

 

oh on stock rims with gforce sports.

 

iGuidance very nice!

your speedo is wrong.

 

i remember hearing ones tho that simple tire inflation will throw your speedo off at those speeds. so if its reading your going faster than you really are, i guess put a little air in the tires to make them just a smigen bigger. dont forget there spinning like a few hundred times a second there. very small diffrense in tire inflation will make a diffrense

 

your speedo is fine, the actual speed/indicated speed curve generally tapers off at higher speeds.

even if the error is static, that equates to like 2mph fast at 60mph, nothing to worry about.