im tryin to buy a set of cragar s/s wheels, and they come in 2 different spacing options. on is 3.5" and the other is 4.5". which will be better for my truck? its not bagged right now, but hopefully in about 6 months. any info will be great. i've put something up on streetsource, but no replies yet. thanks.
mike.

 

Backspacing is very important , that mesurement is from the hub/mounting surface to the back edge of the rim( the inside lip were the wheel weight would be ). The lower the number the further out the wheel will be. 3.5 and 4.5 are not going to be enough . i have factory mustang 17s ( 17x8 ) and the back spacing on them is 5.78 inches and they just clear the fender with a 245/45/17 tire . Iwould go with a 5.5 to a 6.0, if you get the rims from summit racing you can send them back just dont mount any tires . what i would do is get on with a 5.5 and one with a 6.0 backspacing test fit each wheel to see which looks the best. my wheels are the same size as those and they just clear if they were 5.5 i would of had to roll the fender in the rear to clear the tire ( mine is dropped 3 inches and rear tires are tucking a 1/4 of an inch)

I hope this helps!!!