Thor Forums

[Chance]

Single Rear Wheel (SRW) designs are limited more by costs and what is practical than by actual tire physical limitations. There are plenty of large 4-wheel vehicles proving this.

One factor to consider is tire size. Higher capacity tires are usually larger, and for existing Class C van-based chassis, significantly larger tires may not fit under existing bodywork.

Traction is another issue that has to be addressed. For a cargo-oriented RWD truck chassis (like those adapted to Class A motorhome use), dual rear wheels is an easy and cheap way to improve traction when loaded since roughly 2/3 of vehicle weight ends up over the drive axle. By comparison, common front-engine RWD cars often have less than 1/2 of weight over driven rear axle, which limits traction on slippery roads (snow and ice) or if driven off-road. When weight over driven wheels falls much under 50%, traction can become a real problem.

Fortunately, vehicles designed for AWD or 4WD have 100% of weight over driven wheels, so traction benefit of dual rear wheels (due to extra weight over driven rear axle) no longer applies. For this reason, I expect many of the new AWD electric vans rely on SRW design. For now they are relatively small and light, which also favors SRW design.

While it may cost a little more, my preference is a vehicle with 4 identical wheels and tires, provided it is designed and optimized that way from very beginning.

Below is picture of a larger electric delivery step van (now discontinued) which has higher weight rating than new Axis 24.1. Tires look like commercial 19.5-inch to me; but could be smaller.
.