To make a long story short, I bought a set of Halibrand 5-spokes 16x7 with 4.5 in backspacing prior to buying the American Racing TT2's. Well these ran right into the parking brake cable and the rear spring. They weren't available in any other BS. I sent them back and after research discovered that 4in BS was standard.
The TT2's I have now are 4 inch BS and they fit perfect. I don't think you could squeeze 4.25 inch in because that 0.25 inch is about the clearance I have from the parking brake cable. Infact I recently discovered that at some point the parking brake cable was rubbing against the tire. I couldn't find any markings on the tire, so maybe it was from the 275/60-15's I removed. Hard to say.
Then again, you could always relocate the parking brake cable and go with the larger BS.
Why fight city hall...go with what works.