1998 M750 speedometer is way off. ???

[Speeddog]

Hmmm..learn something new every day. 

[brad black]

i'm running a 120/70 on my 600m instead of the std 120/60.  not sure of the direct impact of the tyre change alone, but my speedo was reading 10% low - i got booked for doing 95, thought i was doing 85 sort of thing.  i now run a bike computer - much more accurate.

[clubhousemotorsports]

Most speedos read high from the factory. When you increase your tire diameter the tire makes less revolutions for a given distance than the smaller tire. 120/60 to 120/70 is a 10% increase in side wall so diameter increase.

My experience really came from mounting a set of 33" tall mud tires on my truck when it came with 195/75-15 itty bity tires. My speedo (and odometer) were off a ton . At an indicated 55mph I was doing at least 75mph. oops!

you could correct it somewhat with the correct drive but it still will not be accurate . GPS or bike speedo is best, I just check mine against the police radar and then compensate. [moto]

[meano_lover]

my 97 m900 is the same way- it reads 40 and the police radar (stationary unit- on the side of the raod with the big red display- not in car) reads 44-45. i i just ride a bit slower. it seems to work out fine.