What should you check regarding brake drums during an air brake pre-trip inspection?

During an air brake pre-trip inspection, checking that the brake drums show no signs of overheating is crucial because overheating can indicate severe issues within the braking system. Overheated brake drums can lead to reduced braking efficiency, brake fade, and even potential brake failure, posing significant safety risks on the road. Signs of overheating can include discoloration, warping, or any visible damages that affect the functionality of the brakes. Ensuring that the brake drums are functioning properly is a key component of maintaining overall vehicle safety, particularly when towing heavy loads, as is common with vehicles requiring a heavy trailer endorsement. This focus on the condition of the brake drums is essential to prevent problems that could arise from inadequate braking performance.