What is the most significant factor leading to brake overheating when descending a mountain grade?

The weight of your rig is the most significant factor leading to brake overheating when descending a mountain grade because heavier vehicles exert more force on the braking system. When a heavy truck descends a grade, the gravitational pull increases the speed and requires more braking power to control it. This results in increased friction and heat generation in the brakes as they work harder to slow down or maintain control of the vehicle.

Additionally, the added weight means that the braking system has to absorb and dissipate more energy, which can lead to excessive heat buildup. If the brakes overheat, it can lead to brake fade, where the braking effectiveness is significantly reduced, posing a serious safety risk. Other factors, like the length of the grade, type of terrain, and weather conditions, can influence how brakes perform, but the weight directly impacts the demands placed on the brake system during a descent. Understanding this principle helps drivers manage their loads and braking techniques effectively when operating heavy vehicles on inclines.