Flat wheels refer to wheels that have lost their round shape due to damage or wear. Some synonyms for flat wheels include busted wheels, damaged wheels, deflated wheels, dented wheels, flat-tired wheels, punctured wheels, and worn-out wheels. These terms are commonly used in the context of automobiles, bicycles, and other types of vehicles with wheels. Having flat wheels can cause serious problems for drivers, such as decreased traction and handling, reduced fuel efficiency, and increased risk of accidents. It is important for drivers to maintain their wheels and replace them when necessary to ensure safe and efficient operation of their vehicles.