What wheel offset on wider wheels?

[AnthonyG]

Wanting a more aggressive look for my '35 Ford Tudor. Want to change to wider smoothie style wheels from the stock 16" wire's for a while. If I go with 15" X 7" what should the offset be to clear everything? Suspension stock.
Thx

[deuce_roadster]

Make sure you use the adapters to go from wire wheels to disks, otherwise the lugs will pull unevenly due to the hubs that are made for the wires.

[Uncle Bob]

Tony, hopefully you won't take what I say wrong, but I'll start with an admonition. Take what others tell you as a guide only, not as gospel.........including what follows. You really need to work out what will fit your individual application as these cars were built with comparatively wider tolerances, and with 75+ years of service it's hard to predict what's been moved around. And please, measure both sides as the room available may not be the same from side to side. An 18" straight edge and tape measure will be your friend. Well, that and a decent sense of spatial relationships. Also keep in mind that the space above the tire narrows because of fender shape which becomes important when suspension compresses, e.g. over bumps.

Tire size and shape (aspect ratio especially) will be a factor too. Tire manufacturer spread sheets will list cross section width (what some refer to as "bulge"), don't forget to include that in your evaluation. Just as an off the cuff idea, if you're using a 7" wide wheel then you would typically use a tire with 7" wide tread face which would give you a cross section width of 7 1/2" on up depending on section width/aspect ratio.

Okay, as a guide; on my '36 (I'll post a pic that might help) I had a wider rim mounted to a stock center, in my case I went 16 x 6. After doing the measurements I ordered a 3 1/8" back space (and for reference an 85 aspect ratio tire). Wheel guys usually prefer to use that measurement to define offset. Also, keep in mind that the 6" in my case, 7" in yours, is the inside measurement of the wheel rim opening, not counting the rolled flange edges, which add roughly 1" overall. With my setup I had about 5/8" clearance to the closest component on the frame which left me with decent clearance at full compression of the suspension. Emphasis on "MY". On the face I had a bit more clearance to the fender opening, but slightly less than an inch.

As deuce roadster mentioned, you would have an extra kicker to consider if you still have the '35 drums that have the cast in lugs for wheel center support. I don't have any here to measure but if memory serves that's going to add about 1/4" each side. None of that seems like big numbers, but it's a bit like tolerance stacking, a little here, a little there, and next thing you know you've got rub........or worse.

It may sound complicated, and I suppose in some ways it is given the number of times folks don't put in the effort and end up disappointed cuz they guessed wrong, or took incomplete advice. But it probably took me longer to type all this than it would to figure it out if you have sufficient aptitude.

[AnthonyG]

Sponsored Links (Register now to hide all advertisements)

Thx to both for the caution / INFO. I'm running the stock 16" spoke wheels now. As I understand it the drums have to be as you both indicate to support the '35 wire's. if drums were ever changed to accommodate regular steel rims I would see adapters ( and don't ) to be using the wires I believe?