I also wondered about doing that, but this will happen: "Besides the use of foam inserts in place of compressed air, RC tires are vented and not sealed. The difference is extremely important. If RC tires were sealed, they wouldn’t be able to form around and grip obstacles such as rocks, but even worse, especially with high-speed vehicles, the tires would act like inflated basket balls and bounce when a vehicle landed. Vent holes allow air to escape and return when a tire impacts the ground. Without breather holes, a sealed tire would bounce like a pogo jumps off."