What size tires

[moweepea]

I have a 63 Dodge polara with air shocks in the rear, and 15"x8 steel rims, 4.5 backspace. Does anyone know what is the largest tires size I can fit on this? I think 275x60x15?? Right now I have 235x75x15s and I smoke them up ... Thanks, Harry

 

[5.7 hemi]

275 60 15 for the rear, 245 60 15 for the front.