15x8 Rear Wheel Backspacing?

Hey guys, I want to stuff some 275/60/15 tires into the rear of my '69. The 15x8 wheels I want come in either 4.5" or 5" backspacing. Is 4.5" enough or do I need that extra half inch more? I’m out of the country right now and not near my car to take measurements. Thanks!


Stolen from another Cougar site.

What will fit.

15x7 235/60R15 3.750 70 Rear BFG Radial T/A GatorGreg
15x7 235/60R15 4.000 69 Rear Bill Q
15x7 235/60R15 4.000 69 Rear Cooper Cobra GT ColdCougar Cragar Soft 8s
15x7 235/60R15 4.250 69 Rear Rick
15x7 245/60R15 4.000 70 Rear Bill Q
15x7 255/60R15 3.750 69 Rear Andy S
15x7 275/60R15 4.000 69 Rear Jay W
15x8 255/60R15 5.000 69 Rear n2fordmuscle
15x8 275/60R15 4.250 69 Rear Mike (Old Wood)
15x8 275/60R15 4.500 70 Rear WVcat
15x8 295/50R15 4.500 69 Rear Logan
16x7 225/60R16 4.750 69 Rear Continental Touring Contact Yeloxr7 Grand Marquis Lace-spoke wheels
16x8 225/50R16 4.500 69 Rear Bill Q
16x8 225/50R16 4.500 70 Front Kumho MX Jim K Vintage Wheel Works V40s
16x8 245/50ZR16 4.500 70 Rear Wiley L.
16x8 255/50ZR16 4.500 69 Rear Andrew(atomicbob) 1" lowered Mid-eye springs
17x10 275/40ZR17 5.000 69 Rear John Lewis
17x8 235/45ZR17 4.750 69 Rear Leon
18x10 295/35R18 6.000 70 Rear Rare70cat Boyd Coddington Smoothie Iis


This also depends on a few other factors.

I wanted to put a pair of slicks on my wife’s '70 Mach 1, and normally the 15x8 wheels with the 4.75" offset would have fit the wheelwell nicely, but the factory rear swaybar link was in the way! Dammit!

Ah I see, well no sway bar on my car. Just good shocks and thicker leaf springs with with an extra half leaf. Handles good enough for me. I’ll take the bigger tires if I can get them to fit!

I am looking at rims for my 69 also. Thinking of 17x8 4.5 backspacing 245-40 tire. Going to be real close to the factory sway bar but it looks like you could go to a 5" back spacing to me with no sway bar. Anyone know if same 17x8 rim and tire will work up front?