Originally Posted by
FBinNY
You're doing it the hard way.
They now make 29'r mtn bike wheels and tires. 29'r is mtn bike speak for 700c, so you can go to wider tires up to the limits of your frame and fork clearance without changing your wheels.
I expect the frame and fork clearance are really the problem. I had an '83 Trek 400 that came with 27" wheels but the brakes let me substitute 700c and they gave noticably improved fork and frame clearance. Even then, 700x28 was the absolute largest that would fit and 700x25 with fenders. There is no way fat 29'er tires will fit.