So have a 57 chevy panel. The rear axle has been swapped with a 8.8 from an explorer. Being a panel - the rear wheelwell design makes it a little harder to ensure you dont rub against. So here are my measurements - how do I determine what size wheel I can fit easily and what offset .... so it fills nicely - but doesnt rub. ************* OLD OEM AXLE. ************* 41.5" center of leaf to center of leaf 56" backing plate to backing plate 3" width each drum from backin plate to WMS 62" TOTAL There was about a 6" gap from fender to base of WMS (base of studs on rotor). ************* NEW 8.8 AXLE ************* 39" leaf center to leaf center 54 3/4" backing plate to backing plate 2 1/3" from backing plate to base WMS 59 1/2" TOTAL (this was nice as it is VERY closet to Dakota Front End Measurement) What are the main measurements I need to use to help work out what size/offset would be the best fit to make sure it doesnt rub (too big or look silly (too small).
But thats basically what I mean right -- offset/backspacing. Was thinking to just create say a 16" cardboard circle/wheel cutout and mount on axle. Then measure width to each side until I make contact ...... go from there ...... lets say I get 4 inches going back to the center of vehicle and 3 to the front ..... then need a -ve 1" backspace .......... Or is there another way to work it out .....
You're on the right track but now you just have to get on the right train. (Humor intended, not a put down ) Your tire width is the critical factor, not the wheel so much. Make your cardboard circle the circumference/diameter of the tire bulge (for example, say it's 25"). Then measure from the hub face (the cardboard) both ways to the body work. Chances are the hub face is not the exact center line of the space available. The amount off center is your offset or back spacing. If the tire center is inward from the hub face, I believe that's positive offset. If it's outboard, it's negative offset. If it's dead center, that's 0 offset. I prefer using offset over back spacing because you are working from the tire center. With back spacing, you're working from the back edge of the rim, not the tire. Then you have to deduce where the tire bulge and hub face are verses the wheel center. And you almost have to have the actual wheel in your hands to measure all that. All wheels of a certain advertised width are not exact clones. For example, one 8" wheel may measure 8 3/4" from flange edge to edge and another 8" wheel may measure 9 1/4" due to one being aluminum cast, the other steel and many other manufacturers variations and rounding measurements. Once you establish the offset number for a particular vehicle, all other wheels of the same offset will interchange regardless of the outside rim edge thickness. But not all wheels of the same back spacing will have the center line the same. It's not a big difference but it could possibly be the difference between rubbing or not rubbing if you're stuffing in a lot of tire.
The Wizard is right on. Get the cardboard cut, look up the tread with and section width, and make an attachment for the cardboard out of wire. I use coat hangers. Like this, it not need to spend the money.
If you can get your hands on a 98-2002 16" crown vic wheel it has the 4 1/2" back spacing, it is a 7" rim. It has the 5 on 4 1/2 lug pattern, some Dodge's had this same pattern. Dorman part # on the rim is 939-131.
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