At 245 lbs., I've been running 700x23 tires for 8 months now. The ride is terribly harsh and I have to be very careful to make sure my tires are inflated before every ride, but my rims have stayed straight and true. I've only ever had to worry about deflection when hitting a crack or pothole, but I know how to "get light".

However, after finally finding a set of 28s locally, I can say the difference in ride quality is night and day.