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      06-04-2010, 07:54 PM   #9
Memphis1
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Drives: Z4 SDrive 35i
Join Date: Oct 2009
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Quote:
Originally Posted by solgain@mac.com View Post
I do recall that when I drove my M3 (also with 19" wheels and tires) that the TomTom speed was always higher then my M3 speed-readout.
Quote:
Originally Posted by mcbeee View Post
my M3 , with 19's and the correct aspect ratio as per BMW was reading 7kmh faster then actual speed. My Z4 with factory 19" rims and factory tires reads 5kmh faster than actual speed and my 325Ci with factory 17's is dead on the speed. +/- 1kmh (all measured with two different GPS units. I started checking when everyone passed me on the highway when my cruise was set at 120, the regular speed of traffic on that road).
unless you guys are using dewetron GPS systems, your GPS systems are not accurate. but on the other hand, all car speedos come purposely set a mile off the true speed, they're never dead on.
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