Wheel and tire clearance 66 dart

I found a pair of reasonably priced 29.5/9x15 M/H slicks on CL yesterday and thought that they might fit on my 66 D/Dart that has S/S spings on it. So I did some checking. I don't think they will fit.

I tried a set of 275/60x15 Comp T/A Drag Radials mounted on Cragar SS (#61815 SS-6 STD) rims. This rim has a 4 1/4 " backspace. The rims fit good but the tire either rubs or is very close to the clamps on the springs. The driver side is the tightest fit. Even with rolled wheel lips, you can't get your finger between the tire and the rolled lip. This tire has a cross section of about 11.2 inches.

My thinking is, you'd need a tire with a max cross section of 10.0 inches and a dia of 28 inches. This should clear the front edge of the wheel opening and the wheel lip. I'd use a 15x8 rim with 4 1/4 backspace. This is the direction that I plan on taking.

Just my 2 cents...............