The player's Steel Body Digi-Beetle is given a different model based on its TIRES part, or lack of such.

501TNKA - Plate TIRES
504TNKD - no TIRES installed
507TNKG - Ring TIRES
510TNKJ - Chain TIRES
514TNKN - Aero TIRES
517TNKQ - Gravi TIRES

Aero TIRES and Gravi TIRES cannot be installed in a Digi-Beetle that has a Steel Body, which leaves those models unused in regular gameplay.