Foam tires are often lighter than rubber. If they’re open cell foam, they tend to absorb fluids (spilled fuel, water, etc) and pick up dirt. Some of the foam tires have a rubber skin to prevent this and to make them look more like full size tires.

Dave brown foam wheels are very light but I do not like the way they look.

Treaded tires look more like full size tires than smooth ones do.

I don’t know if they’re better or worse than any other brand; I like the Hangar 9 Pro-Lite offerings as well as any. I think they’re rubber coated foam but I’m not sure.
http://www.horizonhobby.com/Stores/P...PW&BrandId=HAN
Dubro and Great Planes use a small diameter wheel with a really fat tire around it. The Hangar 9s look more realistic (to me) because the wheel and tire seem to be the right size.