Wheel sizes and speed accuracy

[ade]

Following on from dogz_bollox post about speedo accuracy, I've got a 1.2 mk2 and will shortly be fitting 195/50/r15's to me car.

Anyone know what kind of effect will these size wheels have on the speedo (if any)?

Will it read slower or faster after fitting and how do you recalibrate it?

Dont eally wanna get flashed by the numerous cameras round me if its gonna read slower than what I'm actually going at!


Ade

[mowgli]

you get about a 7 % theoretical overall reduction in gearing but the sidewall and the running pressures will even it out
I'll send you the sum

cheers Mowgli

[Aragorn]

http://www.web-cars.com/math/tiresize.html


That site does the calculation for you

it can also calculate somethin to do with gear ratios

final drive ratio or summat

*shrug* - it works anyway

Aragorn

[ade]

thats bloody freaky!
If you go from 13" steelies (I guessed at 145/70/r13) to 15" (my new wheels are 195/50/r15) there can be as much as 10mph difference when u get to 70! Bitch if u live in a speedcam area!
Better adjust me speedo a little...
Tome to pull the needles off :o