wider tyres make it harder to turn, that's why racers started knee down corners and the old timers stuck with using tucked in methods ( I may be wrong though)
I keep with the stock tyres on the FZ but have gone a slightly wider rear on the TDM, i dropped the steering angle and kept the front aspect ratio for easier tipping in.
if your just doing a bar hopper type thing, it won't make a bit of difference