18/7.5 wheels with 5" backspacing with 245/45/r18 tires

18/7.5 wheels with 5" backspacing with 245/45/r18 tires
7.5" wide wheel is pretty uncommon in aftermarket sizes? Usually 7", 8" or 9.5".
However, if that's what it is, it will fit on the rear, too much backspace for the front for that size tire.

I was thinking the tire was fine but that the 5" backspacing might be 1/2" too much.

It will work but will be sucked up in the wheel well pretty good. The tire (IMO) may be be a little tall.

Yeah, will look to sucked in, but probably no clearance issues.