You'll need to look carefully at the clearences around anything like the swing arm at the frame end torque arm or equivalent parts for disk brakes and do bear in mind that everything needs minimum 5mm to the sides and 10 on the rolling diameter as tyres distort at speed or high tempreature. Handling wise the std tyre is perfectly adequate, same size as bmw tourers like I used to ride and those handled like they were on rails, even fully loaded, 2 up plus luggage and doing 90mph on twisty back roads. Other thing is rim desighn / tyre desighn - things can go bang if you push the limmits of the desighn speck, I've had this happen on a 500 and was fortunate to have a sidecar fitted to hold things steady but the forces involved did break about 25% of my spokes before I stopped. If you want to alter much then look at fitting different wheels altogether. (best bet for comstars might be goldwing if they are any wider, if not at least it will give a very firm indication of the max safe limmit.)
