Times two, times three, times four what Kyle said. I believe that changing wheels to allow the use of radial tires is the #1 best modification you can make to your motorcycle.
Seana Morley had Carozzeria wheels, expensive but lighter than stock, and good-looking, since that seems to be a primary concern of yours.
There are various ways to get wider wheels, the minimum size for front wheels and radial tires in the 110-18 size we have is 3-1/2". You can use the OEM rim with a 110 radial tire, but the spread of the beads will not be optimal. If you do that, do not go wider! A good size for the rear is an 18" X 5 or 5-1/2" to not cost yourself top-end. A 17" wheel/tire is often used because of the wider selection of rubber. However you will lose a fair amount of your top end. If you value acceleration over top end, then it's not an issue. Just don't be surprised when a stock rims VMax passes you on top end.
Whatever you decide to do, to enter the radial tire realm, don't mix brands or types of rubber! A mistake like that can turn your bike into an evil-handling witch that you won't have any confidence in.
Radial tires from manufacturers have different methods of construction. One may use an oblique angle of ply wrapping (the plies wrapping across the tire are at oblique angles to the belts running around the tire) while another manufacturer uses a different angle for the plies. (a 'zero-angle' ply wrap across the tire is a wrap at 90 degrees to the belts running around the tire circumference). The handling when you 'mix' methods of tire construction can become very unstable.
Are there people who mix tires from different manufacturers? Sure. Are they all unstable? They may not be, but do you want to buy a tire which has that problem when you 'mix' tires? Even the types of rubber can cause problems. A tire which doesn't heat up to operating temperature as quickly as another tire on the bike, will also cause poor handling. That's why it's a good idea to use the same construction type, and the same rubber type, from the same manufacturer.
Again, do people mix manufacturers' products? Yes. Is it a 'death warrant' to do that? It may not be. But why take the chance?
The 5" width at the rear is about the most you can have without having interference with the swingarm. If you want wider, you will need to do a cut-out of the swingarm (called 'notching') to provide adequate space for the wheel/tire.
