[JayG]

I run 7x17 et55, 7.5 x 18 et50, and 8 x 17 et50 fronts with 20 mm spacers and 8.5 x17 et48, 9 x 17 et52 and 9 x 18 et52 rears with 15 mm spacers with out any clearance problems. I have also put the 20mm spacers on the rear without any issues.
Tire size fronts are 225/45-17, 235/45-17 and 225/40-18 with 255/40-17 and 265/35-18 rears

Front camber is -2.2 and rear is -2.5 on M030 ROW springs so its lowered around 15-20 mm

Don't know where RK got 40 offset as a limit. Wheel width factors in with offset as well

there are a bunch of wheel/offset calculators on the web you can compare dimensions with

Adding spacers pushes the outside edge out and the only issue could be fender clearance. . With my setup, its is not a problem