How fast am I going..?

[Photonboy]

..on a stock wheels & tires '05 Thruxton when the speedo says just under 120mph? I know that the speedometers are not accurate but is there any info out there as to exactly HOW inaccurate they are? Are they calibrated to a certain inaccuracy?

 

[RumRunner]

They do seem to vary a bit, but 10 - 12 % seems to be the norm (reading high) so if you go at 12% would be about 105 MPH

 

[Kirkus51]

+1 on Rummie's comment.

 

[RumRunner]

Mine is only off 10% (vs. GPS & Radar)

 

[Motley]

I believe I found mine to read a consistent 5 km/h high, throughout the speedo range, as compared to GPS.