Right, i used to have 205/40/16's on my car with a ET15 offset, and they to just scrape the rear arches when it squatted.

Now, i have some 205/40/17's with a offset of ET45. I want to bring them out a bit, using 25mm spacers. This would then give an offset of ET20 on my new wheels.

Do you think they will rub because they are larger in diameter? or will they be ok?

Cheers!