I'm considering a set of Work Emotion XT7 in 18"x9.5" +20. I took a look at the wheel offset sticky, and see that I'll be 31mm closer to the outside fender, and 5mm further from the struts/shocks ("18x9.5 ET20 +31/-5").

Will these clear without rolling the fenders at the stock ride height? I'm confused about how to calculate what the maximum clearances are.

Also, I'm considering stretching tires in the stock size to fit until they wear out, at which point they'll be replaced with a proper wider tire. Is this additional 1" stretch feasible? The car may see some track/autocross time this season, which would about end the life of my current tires.

Thanks for your help. I'm kind of new to the upgraded wheels thing, so I'm trying to figure out how it all works.