hello to all
when i got my x5 last year,it came with p225-65-r17 tires tag on door calls for 235-65-r17 according to sites at 60mph it should be 61 no big deal my issue is no matter what gps i use in this vehicle it reads that i'm 10.mph off.so 60 it's really 50 but when i use the same gps on my other vehicle they are on point.
what other test can i do or my speedo really off.??? thanks

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4/02 x5 3.0i AUTO BLACK
KISSIMMEE FL