17’s-How do they effect you speedo

[_Tom]

Is it right that 17s mess up you speedo? If so, do they make it faster or slower??

 

[blink172]

Only if you get the wrong size tyres. im sure someone will give u the technical explanation in a second

 

[Daz]

http://www.miata.net/garage/tirecalc.htmlhttp://www.miata.net/garage/tirecalc.html

 

[Levo]

Goto: http://www.chris-longhurst.com/carbibles/http://www.chris-longhurst.com/carbibles/

In the wheel and tyre bilble section there is a tyre calculator, put in your tyre size, then the 17" tyre size and itll tell you how much difference in speed there will be.

e.g. OLD: 185/55/15 NEW: 205/40/17, Speedo shows 70mph, actual speed 71.35mph

 

[cliosportcraig]

195/45/16 seem to be the closest match to to the valver original wheels !! plus 205/40/17 s are more likely to rub as they are wider !!

 

[Adams_16v]

it will be out, but 17s definately slow the car down!

 

[_Tom]

Very interesting! Cheers everyone!

 

[peter182]

But top end is a bit faster am i right?

 

[RobFenn]

Yes because it gives the effect of longer gearing. However wider tyres cause more drag so it may balance out.

-Rob

 

[Roamer]

And as there is more weight further from the hub it will accelerate slower too.

 

[_Tom]

It seems tuther way round on mine! Seems to accelerate the same but they have killed my top end! With 15s i can get 130+ easily but with 17s i get to 120 - any more and the wind would have to be behind me!

 

[Adams_16v]

top end should theoreticly be faster, but due to the size and weight difference, it will be a lot harder to get there, so no hehe

 

[_Tom]

Just think it losses it power pushin 17s at those speeds! Like i say, when the 15s go on t just keeps accelerating!