New wheels effect speedo calibration

[Sp!ke]

I was just wondering how much a serious wheel change (say 15" to 18") would effect the calibration of the speedo.

Can the speed sensors be adjusted or is the difference so minimal its not worth bothering with?

Anyone looked into this b4?

[V12]

We have put 18's straight on 124 coupes from 15" alloys, and noticed very minimal differences


The car used to top out at 145mph now it only reaches 137-8mph.

Upto around 60mph you will notice no difference on the speedo, then the change is very insignificant.

The worst thing, is accelaration is affected for the worst, but that is still not that notisable... <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

[Mark300SL]

Spike

If you put bigger wheels on - you use a lower profile tyre to compensate for the overall rolling radius.

I have 225/55/16 on my SL now - but the new wheels are 245/45/17 ie the profile is lower and this compensates for extra diameter of the wheel.

Use this link (http://www.miata.net/garage/tirecalc.html) to determine the overall diameter or rolling radius of your intended wheel/tyre combo

HTH

Mark

[Sp!ke]

hmmm..very interesting site that one.

So the answer is I suppose ...if ya do it right it shouldnt matter!

[Koolvin]

damm you midnight monkey's!!

[Mark300SL]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Sp!ke @ Sep. 04 2002,00<img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>)</td></tr><tr><td id="QUOTE">So the answer is I suppose ...if ya do it right it shouldnt matter!</td></tr></table><span id='postcolor'>

Yeah - but there is a limit <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>

For example if the car had 15&quot; on it to start then once you get out to 19&quot; Wheels you are at the very limit and an innaccuracy creeps in
If you go for 20&quot; wheels you cant get a small enough tyre for it not to affect speedo and gearing.


Mark

[Steve_Perry]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote (Koolvin @ Sep. 04 2002,06:43)</td></tr><tr><td id="QUOTE">damm you midnight monkey's!!</td></tr></table><span id='postcolor'>
http://news.bbc.co.uk/olmedia/370000/images/_370807_chimp300.jpg

Ooh ooh ooh <img src="http://www.mbclub.co.uk/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=':p'>

S.

[Koolvin]

http://images.google.com/images?q=tbn:8pVK2nmdrBsC:students.washington.edu/oneil/sa/lol.gif