Rolling diameter of 15" rims

[ashtons99]

I'm looking at a set of Speedline 2118s. 15s for my 182 Cup. Obviously fitting the same width and aspect ratio as the tyre on the standard 16s (195/45) is going to throw my speedo out. To get the right rolling diameter I think 195/50 x15 put me somewhere near, using some calculations I reckon there will be about 5.5mm difference which will make negligible difference if perhaps reading very slightly slow.

I'm presuming it I'm not the first to consider this dilemma but can't find anything on the site

 

[Ol’ Tarby]

πD

 

[ashtons99]

Thanks James
I should maybe have just put it....when putting 15" rims on a 182 what size tyres do people fit

 

[Tim.]

195/50/15 here.

I use GPS/nav for speed, not sure how wise that is but to me it feels more reliable than the speedo, especially when on a non-standard wheel/tyre combination.

Edit:
http://www.willtheyfit.com/index.ph...ct2=50&wheel_size=15&wheel_width=7&offset2=43

 

[Steven103]

Most people use 195/50/15.

The good news is that a smaller rolling diameter will make the speedo over-read, not under-read.

 

[Clio_fool]

My speedo over reads with standard alloys anyway, so if that's the case with small diameter then don't worry about it.

 

[Gus]

I'm looking at a set of Speedline 2118s. 15s for my 182 Cup. Obviously fitting the same width and aspect ratio as the tyre on the standard 16s (195/45) is going to throw my speedo out. To get the right rolling diameter I think 195/50 x15 put me somewhere near, using some calculations I reckon there will be about 5.5mm difference which will make negligible difference if perhaps reading very slightly slow.

I'm presuming it I'm not the first to consider this dilemma but can't find anything on the site

If you have access to renault clip - and you should considering how many RS's you have, then you can change the wheel type and this will sort the speedo out.
Get a cheapy one off ebay for £90 - well worth it.

 

[ashtons99]

If you have access to renault clip - and you should considering how many RS's you have, then you can change the wheel type and this will sort the speedo out.
Get a cheapy one off ebay for £90 - well worth it.

Brilliant, thanks