In what situation will a rider feel an imbalance when the rear tire goes flat?

When a motorcycle's rear tire goes flat, the rider may feel an imbalance, particularly because of the dynamics of motorcycle handling. The correct answer illustrates that the motorcycle will move laterally, which is a direct result of losing traction and stability from the rear tire.

When the rear tire loses air pressure, it no longer maintains the contact patch necessary for proper grip and balance. This causes the weight distribution to shift, leading to instability in the bike's handling. As a result, the bike may tend to sway or move sideways, affecting the rider's control and making it harder to maintain a straight path.

Other scenarios, such as the front wheel lifting or feeling loose handlebars, would typically be more related to issues with the front tire or improper weight distribution, while difficulty steering can arise from several factors but is not specifically tied to a flat rear tire in the same way that lateral movement is. The emphasis on lateral movement highlights the critical nature of balance and traction in motorcycle operation and how a flat rear tire drastically interrupts that balance.