I'm sorry if this has been asked before...I'm ready to purchase a set of rims and tires for my 67. I've done some searches, but haven't quite found what I need yet. I'm looking at Weld Drag Light wheels all the way around. I'm thinking 15 x 7 or 15 x 8 with some sticky tires for the rear. What's the biggest tire I can get in the wells without any mods? I assume 4.5 backspacing? Thanks in advance.