I assume the Tikit has the 16" wheels? I know Schwalbe makes 20" tires with studs. You could make your own studded tires, we used to do it with our rally car tires way back when.

I seem to recall a buddy of mine putting sheet metal screws thru the tread of the tire from the inside and running Mr Tuffy tire liners

But they were damned effective and relatively cheap.
Aaron