i am converting my 91 to a dually and was wondering what the bolt pattern is... did some searches but not really getting a straight answer.... also looking around i looks like the older isuzu/ chevy cab overs have the same bolt pattern.. and since i need to find rims and i dont want to run 14's and i woudl suspect that the rims on the cab overs would be like 15's or 16 or 16.5"... is there any other rims that bolt up.. thanks

 

All the toyota duallies I've seen all had wheel adapters. They went from the norm toyota bolt pattern to whatever bolt pattern is used when converted to duallies wheels

 

but i am talkin about the facotry dually stuff

 

I'm no expert but the 2 that I have are motor homes and they are the small ford 5 lug like on a probe..

 

I take it your talking about using the Toyota 1 ton floater axle with the dual wheels, they used a unique size wheel, 14", 5" width with a 6 lug x 7.25" bolt pattern Theres a few companies around that sell replacement wheels, and possibly still available from Toyota too.
Supposedly, but don't quote me on this, but some of the early Ford and Dodge 1 ton trucks also used the 6x7.25 wheel but in 15" or 16", 16.5" sizes.

 

Another option you should look into is the stock 70s rear dually rim. It was a single 14" hoop, about 13" wide. Had 4 sets of beads and held 2 tires on 1 rim. Had a crazy amount of dish, and used a normal width axle. Something like that may work out for you?

 

Toyota never made a stock 70's rear dually wheel, those were made for by outside sources and used by the motorhome manufacturers back in the 70's to early 80's until the feds mandated a national recall on the motorhomes using them because of axle and axle bearing breakage problems.
On a pickup thats not carrying a lot of weight you could probably get away using them but would need some major fender flares as nearly all the offset is to the outside where the 1 ton floater axle with the dual wheels centered the offset with 1 wheel facing inward and 1 facing outward.

 

91' Toyota Dually Conversion....

I had done this same thing to my 91' Toyota about 2 years ago.....in Manchester, NH. Still have it.
As far as the Lug pattern, no other rims will fit other than the 14" Dually wheels. But you can easily get those wheels from any late 80's Toyota, Nissan flat-bed trucks or Camper trucks.
Unfortunately, choices are limited (Unless you get custom made).

If you want 15" or 16" rims, you would be better off putting a Chevy Dually rear-end out of an old box truck. Those come with 15"/16" rims.
Different lug pattern as well.

No matter which way u go (whether 14" or the Chevy 15"/16" inch. You'll need to do mods to fit. Even the "Toyota" rear-end. Leaf perches need to be moved (Quarter inch) in-ward. Then re-align. Toyota did NOT make a dually, it was separate business that teamed up. Thats why nissan flat-beds have the same rear-end, but different axle cover bolt pattern on wheels.