Bigger wheels/Speedometer

[172gal]

Alright i dont know if this guy i was talking to is talking bull sh*t or what but he says that if i get 17" wheels ill have to go to Rolling road becuase the speedometer will need to be adjusted!! Is this utter nonsense or what?

Oh and if anyone wants to explain what exactly RR is?

Thanks you clever ones!

Hannah

 

[ClioJohn]

so long as you get the correct tyre profile you will be ok.

basically if you get a bigger wheel you get a thinner tyre, which keeps the actual wheel radius very similar, if not the same

RR is when your car is put onto a rolling road where you can get a print out of power and stuff well maybe a bit more complicated than that...but i need food and dinner is ready

 

[172gal]

LOL cheers John. Enjoy your dinner!!

 

[White16valver]

Basically, if you have a bigger diameter wheel, you will travel further on one rotation, therefore you will be travelling faster. So, just do a bit below what you should be doing and you should be fine.

 

[telford_mike]

Hannah. Dont worry. Have a look at <A target=_blank href= "http://www.chris-longhurst.com/carbibles/index.html?menu.html&tyre_bible.htmlthis page. It tell you everything youd ever want to know (and a lot more) about this subject. Scroll down to the tyre size calculator and you can enter the sizes of your original tyres and wheels, and the sizes of your new ones, and itll tell you how much you speedo is out. I have 205/40/17 on my 172, and at an indicated 70mph I am actually doing 71.67, assuming that the speedo was accurate in the first place, which it probably wasnt.

There is no way to recalibrate your speedo to take account of this, and no need to either really.

 

[Black Fox]

Im sure RR stands 4 rolling radius, nothing to do with rolling roads.

 

[172gal]

Telford Mike - Your like a book of knowledge!!! I must say thanks alot, its not the first occassion youve been super helpful! Its much appreciated.

And thanks everyone else, your all fab.

But esp Mike, as he has a red one

Hannah