20" wheels and spedo

[Zeussy]

My VY was 5% out, can get it reprogrammed to suit, either Holden, or someone handy, with the right tools - Phreddy, if you use a GPS make sure its on flat ground, apparently they can't work out if you're going up a hill so it thinks you're going slower than you really are

 

[VS_Pete]

Tire size calculator

 

[DevilDRake]

Well i got 225/35/20 on mine, (being a larger profile, i'm doing 103kph when it displays 100kph), you've got the right size so you should be fine.

 

[ducker85]

Well i got 225/35/20 on mine, (being a larger profile, i'm doing 103kph when it displays 100kph), you've got the right size so you should be fine.

20's with correct tyres make little or no differnce, use a GPS to check your speed, my car was doing 50km when the speedo read 57km after I changed the diff and was 25km out at 100km/ph just check it with a GPS and if your that worried next time you buy tyre get the correct size. Speak to your local tyre shop if the tyre cal. app's dont make any sense.

 

[Daggy082]

225/35/20 or 245/30/20 are two acceptable and legal sizes.