I don't know if the Sorex 20's and 24's are actually belted or not, but I've run Team Losi Yellow compound tires, and so have a few of my friends. These are not belted, and lasted up to 6 months of racing. These obviously have much less grip than Sorex tires (any of them), but they lasted much longer, without belts.
Undoubtedly, the lack of belts would understandably shorten these tires' collective life spans, but their lack of durability seems to stem more
from the design of their tire compound.
*One Q, are belted tires an asphalt thing, or are belted tires good for carpet as well? I would think that belted tires would be best anywhere onroad (foams excluded).*