Introduction:

With the wars in Iraq and Afghanistan it became obvious that a lot of military vehicles suffered from one key weakness: pneumatic tires. No matter how strong a vehicle’s armor, the tires remained the weak link, prone to leaving a vehicle stranded after taking gunfire or shrapnel from a bomb blast. Thus, the US military was clearly in need of an alternative to the current “run flat” tires, which despite the name, still need a minimal amount of air pressure to roll.

Enter the concept of non-pneumatic tire (NPT) or airless tire. Unlike the conventional pneumatic tire, airless tire is not supported by air pressure and their main advantage is that they cannot go flat. Ever since Michelin announced its airless Tweel technology in 2005, several well known names in the tire industry placed a bet in the airless tire race, with a handful of start-ups trying to rival with the established industry players. Resilient Technologies LLC is probably the airless tire start-up which has received the most media coverage in recent years with their distinctive, honeycomb inspired tire design which has become known as the „Honeycomb Tire“. In 2006, Resilient Technologies was granted a four-year, $18 million contract by the U.S. Department of Defense to develop a highly resilient, non-pneumatic tire, which could operate with minimal variation in structural stiffness and a uniform load transmission profile. In April 2008, Resilient fitted a set of their 37-inch tires on Wisconsin National Guard Humvee. The video and photos of this test became widely published across the internet, helping the Resilient tires to their nickname of „Humvee Tires“. That being said, it is still unclear how close to production stage the „Honeycomb Tire“ ever got, as the tire is not found on military Humvees today nor has it been commercialized for civilian use.

(adapted from: http://www.airless-tire.com)

Review:

Replikant Technologies is a fairly new name in the modeling business. The company released several different sets of Schwimmwagen wheels in 1/35 scale, which have all received stellar reviews on various modeling related websites. The latest releases from Replikant feature two types of Humvee honeycomb airless wheels, something most of us would think just isn’t possible to produce in resin.

This review covers both Humvee Airless Wheel Type 1 (350201) and Humvee Airless Wheel Type 2 (350202). Please note I received only one wheel of each type for review purposes, however full sets of Humvee airless wheels consist of:

- Wheels (4x)
- Wheel pins (4x)
- Hub caps (2x).

The first thing that immediately pops out when inspecting the wheels is the incredibly intricate tire design: a pattern of six-sided cells arranged like a honeycomb bordered by a thick tire tread. Another thing to notice is the tires do not feature resin carrier blocks or any casting blemishes for that matter. How great is that; the tires with an extremely complex design which are not only perfectly cast but also ready to use directly from the box? This comes from a revolutionary production process developed by Replikant Technologies, called Resin Injection System. The process enables manufacturing pieces far too difficult to produce using traditional resin casting procedures. Seeing these tires, I would say Replikant definitely has a breakthrough technology in their hands.

The tires in these sets depict non-pneumatic airless 37-inch tires developed by Resilient Technologies for the Humvee. Providing the interconnection between the tread band and the rim, the polymeric honeycomb web keeps the tire structurally sound, while also allowing the tire to conform around obstacles. This design does not only have great load bearing capacity but also helps with reducing excess heat and noise generated during use, and is said to have a ride feel very close to that of pneumatic tires. The NPTs also satisfy their mission profile: should a blast take out 30% of the honeycomb web, the tire will still work.

Replikant Technologies did a great job reproducing Humvee airless tires: the tires are dimensionally correct (remember the airless tire has no sidewall, so these are not classic 37x12.5x16.5 tires but 37x10x16.5 instead) and accurately deliver honeycomb pattern in scale. The tires are slightly sagged, and the sag is visible in the minute compression of the honeycomb pattern. Although the complex honeycomb pattern was digitally designed and 3D printed, the rim was traditionally sculpted. The rim features outer ring with 12 long bolts and inner ring featuring 8 bolts plus a nicely detailed hub cover structure, something most aftermarket Humvee wheel offerings missed. The difference between the two tires covered in this review comes from a variation in tire tread; type 1 (350201) features a tread seen on video and photos of testing the Resilient airless tires on Wisconsin National Guard Humvee widely shared across the internet, while type 2 (350202) features a tread very similar to Goodyear MT tires. I’m not sure if this type was produced in cooperation with Goodyear or not, but I do know Goodyear had exclusivity in supplying Humvee tires to the US Army, so perhaps Resilient changed their tread pattern to match the Goodyear tire. This is just a speculation, of course.

Assembling the tires is easy. The wheel pin is fixed to the rear rim opening, and it fits precisely into Tamiya Humvee axle opening. The hub caps are attached to the rear wheels only.

Conclusion:

Due to the complex design, airless tires are incredibly difficult to produce in 1/35 scale and I think most aftermarket companies wouldn’t even bother with such a task. Replikant Technologies not only accepted the challenge, but did a stellar job on the Humvee airless tire. The tires are dimensionally correct, accurately portrayed and perfectly delivered in resin. Assembly is very much straightforward and the tires fit well to Tamiya Humvee models. The only drawback to these is the fact the airless tires never actually saw combat or widespread use by the military, being in test phases only. However, if you decide to use these 1/35 scale masterpieces on your Humvee, the airless tires will definitely turn into a focal point of the entire model.

Altogether, the airless tire sets from Replikant Technologies are very impressive products. Well done guys!

References:

Resilient Technology
Humvee airless tire test video
Airless-Tire.com