I have a focus ST170 and i will be puttin my Focus RS 18 wheels on very soon. My car will be lowered with Eibach Pro springs kit very shortly to

At the moment the tyres are 225/40/18 but 3 need replacing as the will keep rubbing etc or so i have been told, which therefore leads to my question. Do i need a different size tyre?

I have been told that 215/35/18s are the right size ... yet when i looked in Performance Ford ST170 Modifying section is says 225/35/18.

I also have a sierra cosworth 4x4 which is completly standard but would i be able to use 215/35/18s on that to?

any help would be appreciated

andy

 

standard st170 is 215/45/17...

so as i work it out should be 215/40/18.. or 225/35/18..

so you could use 215/35/18 but a smaller overall diameter could cause underreading of the speedo,,,

 

215/40/18 would be your best bet, i had problems with 225/40/18 rubbing on the shock when cornering.

 

also you speedo should read fine