RE: No foam inserts?
No foams and sealing the tire to the rim might be alright if your just going to run around on the ground without jumping or hitting any bumps. I have tried this with my revo and a set of t-max tires. I took the foams out, glued the tires on the rims so they were air tight and melted the hole shut in the rim. I did this so the tires wouldn't fill up with water when running in the wet grass. Not a good idea. While it did ok running up and down the road, the problem came when I took it to my off road track and hit some jumps. With nowhere for the air in the tire to go when it compresses it acts more like a basketball and just wants to bounce. This set up is also hard on the suspension because the tires usually soak up some of the ruff stuff. I would advise against it, but you can try it, I don't think it will take you long to come to the same conclusion I did.