You can ignore worrying about wheel sizes, apart from drift cars every touring car uses wheels of exactly the same size and offset, after all why make a car that doesn't fit the industry standard wheels. The only thing to watch for is tyres made for the micro buggies, they use the same touring car wheels but the tyres are trued down to 53mm diameter. They still work fine on a tourer, you just usually have problems with ground clearance and they don't last as long.
Every touring car foam wheel/tyre combo is one of two sizes, thanks to their use on nitro cars. Electric cars use 26mm all round, nitro cars use 26mm front/30mm rear. Although usually the only thing stopping you running 30mm rears on an electric tourer is whether they will fit over the upright.
I like the Contact-RC tyres, and they have plenty of choice.
On standard white wheels
Lightweight wheels, lighter but not as durable
Black carbon reinforced wheels, stiffer and more responsive
Electric tyres, designed specifically for electric tourers on carpet
Tyres available direct from Schumacher with the above links, but available through any Schumacher stockist.
I would start with 35 or 37 shore on standard wheels to begin with, and the same tyres all round. If you need more grip replace them with 32 or 30 shore tyres. If your club allows additive use whatever most racers are using, that way you know the additive on your tyres won't react with the additive deposited on the carpet by everyone else and destroy the grip.