Originally Posted by scotch740
Running a smaller tire on one side will have your axle shafts spinning at different speeds. Thus your spider gears are going to be working over time till they go BOOM!
I don't think this is true. Spider gears can spin full speed all day long for 100,000 miles with no harm. That is how a front axle disconnect on all YJs, lots of XJs, and thousands of other 4wd vehicles work when they are running in 2wd. The driver's side axle shaft and side gear spins forwards and the side gear and stub axle shaft on the passenger side are spinning backwards full speed all the time. The spiders are therefore spinning full speed. This is what keeps the front drive shaft and ring and pinion from spinning, which is the whole purpose of the disconnect.
Bottom line is you won't hurt an open diff in the least by running different size tires. It would of course increase the wear on the clutch plates in a limited slip, but probably not much more than driving a comparable distance on a windy, twisty road. Probably shouldn't use 4wd unless absolutely necessary, and in the case if 4wd is absolutely necessary, you would probably have enough tire slippage to compensate. I have no idea about different size tires with an auto-locker. Seems like that might not be a good idea.