If the back of the motorcycle starts to jerk from side to side, which tire is likely to be flat?

When a motorcycle's rear tire begins to jerk or wobble from side to side, it is often an indicator that the rear tire is flat or significantly under-inflated. This condition causes the bike's handling and stability to be compromised, primarily affecting the rear of the motorcycle since it is the rear tire that supports much of the weight and provides propulsion.

When the rear tire is compromised, it can lose traction and create a wobbling effect as the motorcycle tries to maintain balance. This issue typically does not occur with the front tire, as a flat front tire usually leads to more controllable steering difficulties and a tendency for the bike to tip forward rather than create a side-to-side motion. Therefore, when experiencing such symptoms, checking the rear tire is necessary to ensure safety and proper handling.