It’s fun to take note of the car designs in science fiction; whether the vehicles fly, swim, or drive, the designs almost always reflect a certain condition or environment. The same is true with many concept cars as well, with the inevitable auto show appearance of some concept car that seems better suited to filtering the atmosphere on Venus than, say, hitting a pothole. But despite the outlandish designs that populate the auto show circuits and CGI artists’ screens, the biggest obstacle in the construction of these vehicles is safety regulations. Otherwise, building these peculiar sculptures is completely plausible. Even the really outlandish ones.

One of these seemingly problematic features is the wheels, and that is the subject of this piece. As it turns out, the sidewall-less tires with honeycomb-pattern interiors that you often see in science fiction concept art or as entries in military vehicle contests are not as impossible to create as you might think. Known as airless, or non-pneumatic tires (NPTs), these durable, flexible designs are a surprisingly practical and obtainable devices.

Photo: Car Domain

The idea, in general, is to create an adhering surface capable of generating the same (or, more often, greater) gripping properties compared to a traditional tire, while at the same time having the ability to absorb bumps in the “tire” itself. This allows for a much smoother ride, since the existing suspension system is no longer the only shock-absorbing device. Plus, in rough-surface situations, the honeycomb structure of the “tire” enables the wheel to compress more while still maintaining its original shape when returned to a level surface. The only way to do this with a traditional tire is to release the air, a decision that, until you go through the process of pumping air back in, is fairly permanent and detrimental to performance in the wrong situations. As you can see in this video, the difference is quickly apparent.

Whatever your opinions on useful technologies lending themselves to military applications, the non-pneumatic wheel’s non-puncture and tread-like contact patch are perfectly suited to use in harsh war zones. Whether fitted to a heavy truck or an ATV, this style of wheel would create a safer, more reliable transport environment for a vehicle and its passengers. In similar applications, the airless tire would allow for vehicle-led exploration farther afield, in areas where obtaining supplies such as tires is a time-consuming and expensive obstacle. Polar exploration and the maintenance of facilities in Antarctic and the Arctic would be much easier; imagine Top Gear’s North Pole challenge or Volcano expedition with a Hilux sporting NPTs.

But these uses would only be possible if the technology was guaranteed to be cost-effective and reliable. To this end, there are several companies involved in separate pursuits of the design. One is the small, military-oriented (at least, judging by the pictures on their website) Resilient Technologies, who have created examples of the honeycomb-pattern wheels. They even produced that earlier demonstration of the wheel fitted to a Dodge Ram. This design, which is fairly straightforward and appears more hardy (and, thus, military-oriented), allows for flexibility in the wheel, but could limit on-road uses.

This is where the second major competitor comes in. Well-known Michelin has been developing a version of the NPT for some time, and their design is considerably more complex than Resilient Tech’s. For some applications, this may not be a good thing, but for the consumer world, more customization equals a greater potential for adoption. The Michelin design, known as the Tweel, features three or more separate sections between the rubber tread and the hub, as well as in the hub itself. Depending on their spacing, size, and construction, these layers of diagonal rubber supports can provide different shock absorbing properties; in comparison, the RT version has just one pattern from tread to hub.

Photo: Wikipedia

The Tweel principle, like the conventional tire, can be adapted for use in many situations. As with suspension setups, road vehicles could have more forgiving setups, and race cars a stiffer one. Supercars that were previously uncomfortable to ride in over long distances may now have another potential shock-absorbing device at their disposal, allowing for a more comfortable, yet equally responsive, ride.

But reality must now step in. The non-pneumatic wheel is a strange, and inevitably expensive, concept, one that people will be hesitant to adopt early on. The technology may have gained some ground had NASA followed through with its lunar (or Martian) plans, though; the new Lunar Rover uses a custom version of Michelin’s Tweel on its twelve wheels. As we’ve learned from previous space programs, innovations created here tend to get a boost in consumer markets.

Resilient Technology’s simple, more utilitarian design may then be the solution to bringing this wheel to market. If adopted by the military, the idea may filter down to offroad vehicles or specialty vehicle markets. But whether it makes it or not, its interesting to think that this airless tire concept is not just the stuff of science fiction, but a real and plausible solution to flat tires.

Sources:

YouTube

Wikipedia

Wikipedia

Resilient Technology

Car Domain