What are you using the car for (street, drag strip, track days,...)?
What size tire are you trying to fit?
If you choose the right wheel diameter and backspace, contact of the strut tube is not the limiting factor. On the rear, if you have coil-overs, you can run at least 5" of back space with a 15" diameter wheel. I run 15 x 10 wheels with 5.25" back space. With Hoosier 275/35-15 tires I have about 1/2" clearance at the strut tube. As you increase the wheel diameter to 17 or 18", you can increase the backspace of the wheel. The inner wheel tub is the limiting factor for modern (17", 18") diameter wheels.