Maccers

After replacing my standard 16" wheels, that had 205/50 tyres, with 17" wheels, that have 205/40 tyres, I notice that the car indicates a higher speed than what it really feels like. Also seem to be doing more miles according to the ODO readout.

I guess this is because overall my wheel/tyre combination is smaller?

Any fixes other than higher profile tyres?

Boost II

iTrader: (1)

No simple fix - the rolling circumference of the new wheels/tyres is smaller. The nearest to 205/50/16 would have been 205/45/17 and second best is 215/40/17.

There are some tyre size calculators on the web which will let you know by what percentage the speedo is out eg Car Bibles : The Wheel and Tyre Bible Page 2 of 2

According to that, when your speedo is indicating 70 you are really doing 68mph or when your odo says you have done 10,000 miles then you have only really done 9745. It is not a massive difference though?