Originally Posted by focusmaniaczx3
why do you have to go low to run a 17x8? im on factory SVT springs and had/have no problem. optimal offset for a 8 inch wide wheel would be between 41mm and 43mm. that would put the wheel as close to the inner shock as possible without rubbing the shock and it would come close to tucking it in the fenders. it still wouldnt quite tuck under the fenders though which means you would still rub a bit when you hit a bump really good. a slight rolling of the fenders would probably solve that. i just finished doing a fair bit of research into this subject because i am looking for wider wheels for better traction.
the cobra wheels you saw rolling around were likely factory 5 spoke SVT focus wheels. they are 17x7 et 45 i think.
think of offset like this. the lower the number the more the tire is going to stick out of the fender wells. the higher the number the more the wheel is going to be tucked up inside the fenders.
The factory SVT Focus wheels are ET49.
And you on stock suspension are about an inch higher than he is, so even though your spring rate isn't as high the likelihood of your tire coming into contact with the fender is less likely than his is. The idea of going lower is it will add natural camber while also increasing spring rate and ergo travel.
And I'll stick to my suggestions of ET40-42, not that there's that much difference between your suggestion, but ET43 doesn't work with some coilovers in the rear so 42 is a more universal guide to fit.
If you want to fit more wheel under your car that's great, I've got 17x8.5 ET39 wheels with spacers front and rear to ensure fitment. I run 215/40/17 tires with no issues, although I run more camber than the typical focus owner.