Airless Tyres

The next evolution of the humble vehicle tyre is on it’s way! Tyres have come a long way since the start of their life when they were solid and wrapped around a steel or wooden rim. In fact the earliest known “tires” were made of leather or steel and held the wheel components together.

It was during the late 19th century that Robert Thompson and John Dunlop separately created a rubber pneumatic tyre with an inner tube holding the air cushion. This was after both Charles Goodyear in the US and Thomas Hancock (not Hankook!) in the UK had patented the vulcanisation of rubber – the process of making the natural rubber into something more durable.

Most tyres, certainly on cars and motorcycles, have a tubeless construction with a myriad of compounds used for different purposes and most are radial. Read this description of the difference between radial and cross-ply design.

Tyres on vehicles provide two main purposes:
– they provide all weather grip to allow the vehicle to travel safely on roads of any condition.
– they also act as a first line of suspension by absorbing a portion of the shock of a rough surface.

However, as with any automotive component, research is always ongoing to find a better solution. Airless tyres have been developed over the years to ensure that the biggest problem with pneumatic tyres is fixed – a flat tyre! It is a throwback to the solid tyres of old, with a modern twist. Rather than being fully solid, they have been designed with a structure that allows some flex in the tyre but manufactured with more modern materials.

In 2005, Michelin produced the “Tweel” a combined wheel and tyre using polyurethane spokes connected to an outer rubber tread. This gave the best of both worlds, providing the rubber for grip and the spokes to absorb the bounce of the vehicle. There was nothing ground-breaking here in that this is what a motorcycle wheel would do. What was new was that this was one combined unit with the added advantage of improved water clearance through the tread design – water could pass through the tread, keeping more of the surface on the road. The Tweel was fitted to Segway’s, mowers and light construction equipment where punctures are costly.

Not to be out-done, Bridgestone also developed their own airless tyre – the second generation coming out in 2013. This was a similar concept to the Tweel but with a mesh-like spoke structure that allowed the tyre to support the weight of the vehicle. These are not yet available for consumer use, however Bridgestone claim a reduction in CO2 emissions in their testing.

Hankook have followed Bridgestone’s ideas and produced the iFlex which they are testing. Their claim to fame is that they are using a material that is energy efficient to manufacture and is recyclable. However they are keeping the name of the material a secret!

Airless tyres are becoming common in the mining and construction industries where down-time is very expensive. To resolve this problem, Big Tyre Pty Ltd in Queensland Australia, has developed several versions for very heavy machinery which is actually a non-solid wheel with a rubber hoop attached for the tread.

A “non-solid” wheel appears to be a new modern term for a wire wheel – which have been in existence for at least a century or more!

It is only a matter of time before we see a consumer version of airless tyres hitting the markets especially if they can be “green” and reduce emissions either through usage or in the manufacturing process. Like other technologies, we might see the tyre go full circle!