Ok. I have a Fiesta ST. Currently has the standard alloys, which are 17x7 with an ET52.5 or something, and I also have a set of 12.5mm axle spacers on the rear already too.

Basically, I'm looking at another set of wheels, which are Available in ET45 or ET38.

I was wondering a couple of things.. Rather than go for just 17x7, could I fit 17x7.5? and if so what ET would I need? If not, what ET would be best with the 17.7?

I really cannot understand how all this works, and I've sat playing with an "offset calc" on some website..

Any help would be greatly appreciated!
Jay.