OEM wheels 7" or 8"?? Tire experts needed

[ninefourteener]

Long story short, I'm researching wheels/tires for the brat, and I'm going with a 15x8, with a zero backspace.... should fit nicely.

Tires on the other hand... are causing problems.

The tires on the wrx are 235/40/18s..... on 18x8 rims... they fit nicely

The tires on the Tribeca are 255/55/18... on 18x8 rims.... and hang over, and are TALL.

The tires on the SVX are 225/50/16s..... and they fit nicely.... which is why I'm thinking they are 7" wide rims.... correct?

I "wanted" to go with a 225/50/15 tire for the brat (15x8 wheels).... but I'm thinking the tread will look too "skinny" for the wheel.

But..... if I go up to 235 or 245 tires.... the only thing I can find are tall SUV tires.

I cannot exceed 24.5 inches in TOTAL diameter..... the 225/50/15s are right at 23.9 or 24 depending on brand.... which would do nicely... except I'm thinking they will look skinny.

Suggestions?????