Q: speedometer on 1993 Chevrolet Blazer

Rookie cbe0621eac06868b3efe0d8d1d3611e23c60d3114864ea2ec19a68cfbd3eebab
i have to go 30m.p.h. in order to go 25 m.p.h.
i don't really know how fast i'm going.
what could be causing this?
(1) Answer
Is this something that has just started or has it been going on for a while? Changing the transmission, final drive, or tire size can affect the accuracy of the speedometer. If everything on your truck is original and the speedometer is still off, the fault may be with the speedometer itself.