20X9.5 in rear w/ a 265/30 and a 20X8.5 f w/ a 225/35 or 245/30 would be cuttin it real close... I know the fronts should work, I had 20x8.5 w/ 225/35 on my jetta, it was lowered 3" too. I believe you are right on the 42 offset...Whose car is it? I may could swing by MM and let the test fit one of my 20x8.5 w/ 225/35 off my passat for a offset and tire check.