GPS accuracy

[sseaman]

For those of you that have used GPS units for MPH, how accurate do you find them? I borrowed a friends TOMTOM since changing to a larger wheel and at 70 on the GPS the speedo is at 68. The tire size was 225/75/15 to 31.10.5x15. I would have expected closer to a 8%. I wish I would have checked with the stock tires on but to late now.

 

[LINY4Runner]

The factory gauge cluster will normally show 3-5 miles per hour faster than the vehicle is actually moving.