A modern car tire does not have an inner tube. The tire has an internal liner and bead bundles on the inner edges that seal the tire to the rim. This keeps the tire on the rim and allows it to be filled with air. This means there is no need for an inner tube. Heavy construction equipment, trucks and buses still use tires that require an inner tube. Proper tire inflation is important for the safety of the vehicle. It can affect gas mileage as well. It is a good idea to check tire pressure on a monthly basis.