The simplest solution is don't mess with what's not broken. Find a shop to change your tires or do it yourself. Up here it's no problem at all. Check around some more, try big truck shops and tractor places, road side tire service for truckers too.
Easy to find and pretty easy to swap axles with 10 lug on 7.25" bolt circle come under P-30 chassis and 3500HD chevy's (when HD meant something).
Look at the options here
http://www.stovebolt.com/techtips/bigbolts/p30swap/One consideration is it's not recommended to run disc brakes (those rears have them) on the rear if you don't have them on the front as well. Not sure how important that is or what can be tolerated with a proportioning valve and slow speeds?
The Dana 70HD can accept gear ratios from 3.54 down to 7.17. what you'll find will more than likely have 4.56, so you'd be swapping gears or not hauling 10,000 lb.
The Dana 80 can get only as slow as 5.13 or perhaps 5.38.
Also some of the original 1.5 ton axles/brakes will fit in a 19.5" wheel.
I don't think 19.5" wheels look very good on an AD bigbolt though
Grigg
