Tread on me: The wildest tires and wheels around

Sometimes it's not rubber that meets the road. Radical concepts imagine a world where cars roll on resin spokes, flats are a thing of the past and tires change shape to meet the demands of the ride.

When tire maker Michelin looked to the future, it imagined a tire that looks more like it was grown than manufactured. Michelin introduced the Vision concept, a combined tire and wheel, in 2017. The structure is derived from materials that are organic, biosourced, renewable and easily recycled for other applications," Michelin says.

The Vision is meant to be "recharged" with a 3D-printed tread as needed. The tire would also be embedded with sensors designed to detect road conditions, maintenance needs and performance.

This might look like a weird basketball, but it's actually Goodyear's spherical Eagle 360 Urban concept tire from 2017. The 3D-printed tire uses a polymer that stretches like skin. Embedded sensors keep track of changing road conditions. It's a fascinating idea, but the round shape wouldn't fit with most current vehicles.

Bridgestone showed off its unusual Air Free concept tire at the 2014 Paris Motor Show. As the name suggests, you don't need to pump up this tire. The outer tread is just a thin band of rubber, while the shock-absorbing "spokes" are made from resin. Every part of the concept tire is recyclable.

Bridgestone isn't the only tire company with an airless tire. Michelin's Tweel airless radial tires are available for applications ranging from lawn mowers to golf carts. The spokes are made from a high-strength poly-resin and make the tires less "bouncy" than regular tires.

These tires flew into space on the Space Shuttle Endeavour's last mission in 2011. NASA says the tires aren't much larger than a truck tire, but are made with a minimum amount of tread to save on weight. The tires were designed to touch down at speeds of up to 250 mph (400 kph).

Yes, this is a real wheel. Ronal offers these infamous Teddy rims that feature smiling bears. The wheels are currently available in some European markets, but there are some older sets still on the road in the US. They're definitely a departure from the norm.

This isn't your typical Earth wheel. The image shows a close-up look at a wheel on NASA's Mars Curiosity rover. You can see the damage inflicted by the rough Mars landscape. The rover's wheels are made from aluminum, which is tough stuff, but still not tough enough to completely avoid the stress of rolling over rocks on the Red Planet. 

The aluminum wheels on NASA's Mars Curiosity rover are taking a beating on the Red Planet, so the space agency is looking at alternatives for future rovers. One possible solution could be found in this superelastic Spring Tire originally developed in partnership with tire maker Goodyear. 

The latest version of the Spring Tire uses a shape-memory alloy that bounces back to its original form even after rolling over a brutally rocky test track.

Electric cars still get a bad rap for their limited range between recharging stops. Goodyear's 2015 BH03 concept tire runs with the idea of taking heat generated while driving and turning it into electrical energy that can be used to recharge a vehicle on the go. It's a nifty concept, but don't expect to see these on Teslas anytime soon.

Dubai-based tire company Z Tyres wasn't content with plain black tires, so it created a special set of four Z1 tires decorated with 24-karat gold and diamonds. Italian jewelers set the bling onto the tires. 

In 2016, Z Tyres announced that Guinness World Records certified the tires as the "World's Most Expensive Set of Car Tyres." The tires sold for a whopping $600,000 (£444,000, AU$793,000), which could buy you several Ferraris. 

This massive Firestone tire dates to 1942, when it was considered the largest tire in the world. It clocked in at 9.5 feet (2.9 meters) in height and was used for earth-moving vehicles that helped construct airports and army camps. The worker inside the tire gives a good idea of its impressive size.

This 2014 concept from Goodyear doesn't look like a regular SUV tire. The outer ring is wider than the inner ring and each ring has different textures on the surface. The outer ring comes into play on smooth pavement, but the grippier inner ring sees action on rougher roads or softer surfaces. The two rings also have separate air chambers so a puncture in one won't impact the other.

Smart tires may be the future of driving. Tire maker Continental unveiled an intriguing concept tire in 2017 that can change air pressure as needed.

The ContiAdapt tire uses small compressors that inflate or deflate the tire to match weather and driving conditions. Higher pressure is suitable for dry road conditions, while lower pressure can help with traction in the snow. 

Hankook revealed the iFlex, its concept for a no-flats tire, in 2013. The eco-friendly tire is mostly recyclable and doesn't require any air pressure. Hankook says the tire can improve fuel consumption and reduce riding noise while providing good shock absorbency.   

Hankook's eMembrane concept tire is a clever shape-changer that Hankook describes as having "optimal friction variable tread." That dip you see in the middle expands outward to create a fuller tread as the vehicle speeds up. This feature reduces friction and improves fuel efficiency at low speeds, but then increases grip at higher speeds to boost driving performance. Think of it as a mood-changing tire.