I've been riding a rear 32H CR-18 since December. I was 300lbs when I started on it, and I would carry up to 50lbs of books and groceries on my back. Down to 275lbs today, and the wheel is still as true as the first time I spun it around. I have been running a 700x28 tire on it, but I plan to take that down to a 25, there will be no problem with that fit.
Can't say these were all do to weight, but I have broken many parts without bouncing them off of the road or cars, etc, including: Chainrings + Crankset, Casette Cogs, Handlebars, Hollow Axle, Touring pedals