Piston Slap: A Primer on Wheel Offset and Backspacing

It depends on the actual wheel in question. Since you say that the OE wheels were 6.5" that would mean that you have the aluminum wheels. Those are +6mm offset though there are some +8mm that were used too. It is marked on the inside of the wheel. The steel wheels on that era were 0 offset. The 16" "lacy spoke" wheels mainly found on the HPP cars used 0 offset. Are the Ranger wheels factory units and what year are they from? the early Ranger used a smaller wheel center bore than the Panther so they will not bolt fit even though the bolt pattern is the same. They also used a 0 offset. I put a set of my old 92 CV wheels on my mother in law's Ranger because tires that fit the 14" wheels it came with are not that common any more are there isn't much selection.

The rears are definitely not OE Mustang wheels. That era Panther uses zero or minimal offset wheels. To put the new edge Mustang wheels on them you need to use spacers. 1" is what is commonly used but if you want to really tuck tire like that one a little smaller spacer is good. On my 92 CV I was able to tuck some 255/45-18 front 285/45-18 rear on 18x9 AFS Mach 1 replicas that come with a 25mm offset, instead of the 30mm that comes on the stock 17" versions. For the front I use 1" spacers and 3/4" spacers in the rear. My car sits about as low. The featured car looks like it is running the OE 17" Bullit wheels up front and the aftermarket 10.5" wheels. I ran the OE 17" Bullits on mine for many years.

@Scoutdude Yeah, that's certainly not my 92 Vic pictured! It sounds like you got away with a cons1derable offset difference w/o any undue strain on bearings or other components. For the record I haven't changed wheel bearings in 7 1/2 years and I can't find record of the previous owner (the only previous owner) doing it either. No grinding or popping to be heard either. The folks at grandmarq.net were fairly helpful, none of them thought that having these rims on the Vic would be unduly harmful, especially as the tires/rims sit a little inboard perhaps on account of the 5.5 inch-wide rims. They say that wheels that stick out a lot tend to do more damage to wheel bearings.

@86er No I did not get away with a big difference in offset I used spacers to keep the offset the vehicle sees within the range that it saw with factory wheels. A +25mm wheel with a 1" spacer means that on the front the offset the vehicle "sees" is -.4mm or close enough to the 0 offset used on the steel and 16" wheels in those years. On the back the combination of the 25mm offset and 3/4" spacer means the vehicle "sees" a 6mm offset or what the factory 15" aluminum wheels were in 92.

@Scoutdude It just keeps getting more confusing!

@Scoutdude OK I'll see if I can clear up some of the confusion. The thing that matters is the actual wheel center line to wheel mounting surface, ie rotor or drum. A given wheel bearing, suspension and steering system is designed with the location of the wheel center line in mind. Another way to think about is to mentally weld the spacer to the wheel and then measure the new effective offset.

@Scoutdude I should have clarified my 'GT/Cobra variant' phrase as I had, in my head, meant that it included aftermarket replicas that took the spoke design but modified the barrel/rim width. I agree the wheels on that white Vic look like New Edge Bullitts (and not GT or Cobra wheels), but with a super deep dish for the rears. Not really many or any CVs showing up on an image search of your era car with Mach 1 reps. How did you like the look of them compared to the Bullitts? Did the ride suffer going from 17 to 18 or was there still enough sidewall to mitigate that change, or at least make it less drastic? I think my favorite wheels on a newer Vic are the GT500 wheels from around 2010--the narrow split five spoke ones. There's a guy with a black CV, lowered just right, with those wheels (with spacers) and it just looks right.