Inaccurate speedo--not tire related

[BryanD]

I have a new to me 2000 T4R limited. My tires are 265/75 R16 (minimally larger than stock). The speedo is consistantly 5 mph slower than actual speed as determined by GPS. This discrepancy holds true at any speed (that is, always 5mph off regardless of speed). From a stop, the needle doesn't start moving until I'm moving faster than walking speed.

I certainly understand that tire size will effect speedo reading by a percentage, that is, the discrepancy between reading and actual speed increases as speed increases. My discrepancy is a constant.

Make sense? Any thoughts?

 

[nevada]

I have a new to me 2000 T4R limited. My tires are 265/75 R16 (minimally larger than stock). The speedo is consistantly 5 mph slower than actual speed as determined by GPS. This discrepancy holds true at any speed (that is, always 5mph off regardless of speed). From a stop, the needle doesn't start moving until I'm moving faster than walking speed.

I certainly understand that tire size will effect speedo reading by a percentage, that is, the discrepancy between reading and actual speed increases as speed increases. My discrepancy is a constant.

Make sense? Any thoughts?

from the factory the speedo may read a tiny bit slow. its very difficult to make it exactly right on, so when they have to err, they do so on the slow side. IIRC, they are allowed up to 7% discrepancy. the slightly taller tire will only make it a bit worse.


that said, if the speedo doesn't start moving right away, you indeed may have an issue. are those ran off the wheel speed sensors on that rear? I cant keep track....