curiousity really....this is based on a cav v6 police car.
Now, I think the police used to run 205/55 R15's on mine (and the speedo was calibrated to that), but I've got 205/50's all round on mine now.
I had a bit of a blat at the weekend and noticed some wierd things when I peak out...
2nd gear @ 6500rpm = 65mph - thought it was suposed to be like 75mph (on my old v6)
3rd gear @ 6500rpm = 100mph - again thought it was 110mph on my old v6.
Will the tyre difference cause this speed difference???