I’m concerned about the braking distance. Won’t the tires and brakes wear quicker on the Ascendant with a single rear axle than an aerial on a tandem rear axle?

Comparative braking studies demonstrate the 56,000-lb Ascendant stops 50' shorter than a 72,000-lb 105' tandem axle aerial. So you may ask, how can a truck with two axles (one front axle and one rear axle) stop in a shorter distance than a truck with three axles (one front axle and two rear axles) and more brakes?

During heavy braking, weight is transferred from the rear axle to the front axle. We can feel this effect on our bodies as we are thrown against the seat belts. Because a deceleration force acts at the center of gravity of a vehicle, and because the center of gravity of the truck is located somewhere above the ground (the center of gravity on an aerial is even higher), weight will transfer from the rear axle to the front axle in direct proportion to the rate of deceleration. In so many words, this is the effect of weight transfer under braking which can be as high as 70% or more. This is why most vehicles have larger front brakes.

When it comes to aerials, the center of gravity is much higher and the weight is much greater than an automobile, consequently the impact is also greater. In the case of a 56,000-lb Ascendant, over 39,000 lb (70% of 56,000 lb) of force can be on the front brakes. Compare that to a much heavier tandem axle aerial weighing 72,000 lb, which could apply 50,000 lb to the front brakes. Consequently, the heavier vehicle will take longer to stop and exhibit higher brake and tire wear, increasing its cost to the owner over time. Furthermore, all rear tires, brakes, axle, and springs on the Ascendant are rated for 33,500 lb continuous duty (not intermittent use like the 35,000 lb rear axle).