Over the past 100 years, many things about the automobile have advanced. Safety, fuel efficiency, and price—they've all improved dramatically. But one thing that hasn't been revolutionized is the tire. Sure, we have advanced compounds to optimize fuel economy and traction in the snow, but at their core they're just piles of air, surrounded by a rubber donut.

Hankook Tire thinks we can do better. The South Korean manufacturer has been developing a non-pneumatic tire for a while. We first saw the concept in 2013, when it was one integrated unit, combining tire and rim in one.

Now, Hankook has completed initial testing on its fifth-generation airless tire, dubbed the iFlex. The tires do not require any air pressure, instead relying on a new type of eco-friendly material (the company demurs when asked for details). Geometric shapes built into the material provide the bounce and springiness normally provided by air pressure. But, unlike the previous iFlex, this version's designed to mount onto a traditional rim, making it compatible with current vehicles.

Hankook ran the iFlex through a battery of tests to compare it to more conventional rubber, measuring durability, hardness, stability, slalom and speed, at up to 80 mph. The company says the tires matched conventional tires in terms of performance.

Hankook isn't the only company working on airless tires, either. Bridgestone has an idea for a tire that looks like a psychedelic spirograph and a company called Resilient Technologies is working on a prototype aimed at wheeled military vehicles—tires that can't be blown out would be useful if you were under attack.

The company wouldn't make any predictions about when the tires might hit the market nor what pricing would be, but if the Korean manufacturer has anything to say about it, the days of flat tires might soon be over.