Wow after reading this i borrowed my friends GPS system which can tell u how fast u are going and my speed is just off by 3-5 mph, but im going to be putting back on my 17's back on my car after the winter. O btw toy civic how u like the toyo proxes 4 on ur car? i currently have falken ze512 and the road noise is horrible, i was thinking the proxes 4 will be better.