I've got 31x10.50/15s on my stock suspension 94 2wd. No rubs. Rides nice, sits better.
I've been using this for years.
http://www.1010tires.com/tiresizecalculator.asp
those 31s equal to just larger than a 265-75-15
A 275-50-15 equals to 25.8" tall, 10.82" wide. That's pretty short. It'll be losing around 15% of the final drive ratio to the 31x10.50 and about 9% to the stock 225-75-15. The easy way to explain it is that if you truck is going 100, the speedo is going to read 110. If the truck is 50, speedo is 55. But since these trucks speedos are already over compensated when you are doing 50 the speedo is going to read around 60. Also, the RPMs will be higher and the odo will be incorrect.
The shop I work for does about a million a year in performance tires and we have noticed that the actual dimension of the tires vary greatly depending on the manufacturer. An example is that a 255-35-20 Nexon N3000 is visibly smaller in all dimensions to a Nitto NT555 and the Nitto is smaller than a Toyo Proxes4 all in the same size.