I have searched and found that the 15x7 and 15x8 canyon both are the same on the inside of the rim, but because the 15x8 is, well, an inch wider, it will stick out farther on the outside. So, it makes no difference which wheel you run (7 or 8), if you're gonna rub the LCA, your gonna rub it. But the 7's will make the tire stand a little taller. Did I understand that correctly??

 

Maybe a matter of 1mm. Go for the 8" rim for 1" wider stance and 1/2" more clearance from the control arm.