Wheels and Tyres
The choice of wheels is a complicated one. The tyres of choice are the Michelin Solar Car Radials. They are not available for sale and are only available through sponsorship deals. The other likely choices for tyres are (in rough order of likeliness) motorcycle tyres, bicycle tyres and car tyres.
The Michelin Solar Car Radial tyres (apparently) fit a 16 x 2.15 inch motorcycle rim. They run at a fairly high pressure to reduce rolling resistance.
Motorcycle tyres are a relatively good second place to the Michelin. They have a higher rolling resistance and weigh more. They are however much more robust with a motorcycle tyre lasting as much as 10's of thousands of kilometres on the road.
Bicycle wheels, tyres and associated components are too fragile for any large vehicle. Very light solar cars may be able to get away with them but evidence suggests that you will suffer a lot of broken spokes, flat tyres and braking performance will be insufficient.
Some of the solar cars have used small car tyres, but generally these would be considered too heavy and inappropriate.
For wheels there are several options. You can make your own out of aluminium, carbon fibre or if the budget permits, esoteric compounds. If off the shelf is more your scene, there are motorcycle rims and bicycle wheels.
We have chosen motorcycle rims. The specific choice of wheels was made based on the brakes available and the desire to allow ourselves to use the Michelin Solar Car Radials if necessary. We went out to find 16 x 2.15 inch rims that had drum brakes. Drum brakes remove the brake pads from the braking surface under normal operation. Disc brakes leave the pads just riding on the braking surface adding a small (or large) amount to the rolling resistance.
Our efforts to find 16 inch front wheels with drum brakes was a complete failure and we ended up going for Suzuki RG250 front wheels with disc brakes.
For the rear wheel we eventually found a Yamaha XS250 rear wheel that was 16 x 2.5 inch. The theory is that the Solar Car Radials (which we decided we can't use because our car weight more than 3 x the 100kg rated limit for the tyres) would probably fit onto this rim anyway.