Tyre sizes??

[turbo-tastic]

Please forgive me simple brain, but am I right in thinking that I should be able to get 205/55 15 tyres on wheels that currently have 195/55 15's??

I have used the www.rochfordtyres.co.uk/TyreCalc.asp and all seems ok with rolling radius etc (for odomemter & speed etc) but I wanted to check that they would actually fit on the rims??

Is there more danger of them coming off??

All comments appreicated, unless its to tell me I'm thick. I know that already!!

Cheers

Ed.

[iaint]

What's your rim width? That's more important to the ability of the tyre to sit safely on the rim. The width and profile are what'll alter your speedo reading.

For example... the standard wheels on the FD are 225/50/16 with 7 or 8" rim width.

I'm running 235/45/17 8.5" front and 255/40/17 9.5" which gives as close as possible rolling radius to stock. I've got a spare set of wheels that are 7.5" width (17" diameter) that I'd like to put some trackday rubber on but they won't safely fit 255 width rubber (or it's at the edge of the margins so not comfortable to track).

[turbo-tastic]

Right then

SXOC Chairman said:

Standard S13 wheels are 6" wide and 205s will fit ok

So I guess that's that answered then

Unless anyone has any thoughts/comments about fitting 205/55 tyres to 6" wide rims??

>> Edited by Turbo-Tastic on Thursday 19th January 16:06

>> Edited by turbo-tastic on Thursday 19th January 18:46

[turbo-tastic]

Ok, I have also posted this on the SXOC, but I need as many opinions as possible

Turbo-Tastic on the SXOC said:

I need a new set of tyres, but dont know what size to go for. The standard size is 195/60 15, but I found in the S13 tech section that 205/55 15's are even better (bigger footprint etc) But they seem to be quite expensive for 15" tyres, especially if you compare them to 195/50 15's (the more common Barryboy Eurohatch tyre size) e.g. Yokohama A539 V rated 195/60 15 £76.60 205/55 15 £81.43 205/50 15 £82.16 195/50 15 £42.22 Pretty much (give or take a few quid) half the price I've used the Tyre Size Calculator and it says my speedo will be out by 6%, meaning I will be going slower than my speedo is reading (which is a good thing) But it also means that my Odometer and trip meter will be out, making it hard to calculate MPG etc. Basically, if you were me, what size tyre would you go for?? Cheers Ed.

>> Edited by turbo-tastic on Wednesday 1st February 11:11

[Turbo T]

edited because I read the above wrong.

>> Edited by Turbo T on Wednesday 1st February 21:02

[rotarypower]

the footprint changes shape if you increase the width of the tyre on the same rim. On my stock FC wheels (which I have as spares) the rim is a 7" and the stock tyres are 205 60 16 I swapped the rears for 225 55 16 and that was fine but the tyre supplier did say that although the footprint is technically larger, it becomes more diamond shaped if you increas the tyre width (basically the sidewalls become slightly curved)

[tuttle]

Have had similar experience fitting *over-sized* tyres to rims. I found it necessary need to experiment a little with tyre pressures & then monitor them regularly & with care. As RotaryPower says, it'll slightly change the shape. So if you over inflate, even by 1-2 bar the central section of the tread will slightly *bow* & wear very quickly, the same goes for the tyre shoulders if under-inflated. This may also mean that you're not making optimum footprint to tarmac contact under cornering load.

[Mr E]

205 on 6" wide rims?

Rims sound a little narrow to me. That's a 20cm wide tyre on a 15cm rim.

Sure you don't mean 7" rims?

My car stock wort 215s on 7.5" rims. I now run 225 on 8" rims.

[turbo-tastic]

No, they're definatley 6" rims.

I have decided not to go with the wider tyres, due to all the above mentioned problems, but instead I have gone with the 195/50 15's.

OK, it means my speedo, odo and trip meter will be out, but the speedo will read 6% faster than I'm going, so its not exactly dangerous. It also means from now on, my car will do 6% more miles, but I cant see it making much of a difference to the value etc, as long as I remember it should be ok.

But, it also means that I can afford to put nice sticky Yoko A539's on, with a lower sidewall, meaning better handling (slightly), so I'm happy. And £168 for 4 tyres fitted cant be bad can it.

Next on the list is some Anti Roll Bars....