Filling the tires with something other than air, to avoid puncture hassles?

Question

I'm asking because:
- I've had flat tires four times in two years and it has been very annoying.
- The entire family of an acquaintance died when their car tire burst and the car turned turtle on a highway.
- People deliberately throw nails on certain roads.

Started searching for solutions. Found tweel and rubber foam. Made me wonder why they aren't yet widely available for us to use yet. The other alternative was tubeless tires, but even these need air.

On wondering if there would be a foam that could be filled instead of air, I found tire mousse, but these are too expensive and available only for Michelin tires.

The better solution according to me would be to have tires that are as strong as tubeless tires, but with a spongy or springy filling material instead of air. Has anyone here tried this or known anyone who has tried it?

A material that:
- Would not be too expensive
- Would be able to support the weight of the vehicle and the rider
- Would be easily procurable
- Would not add too much weight to the tire
- Would not compromise on traction or safety
- Would be able to dissipate heat reasonably quick for a continuous commute of approx 40Km

Answer 1

What about a tire that was built radially (like spokes on a wheel) and was constructed from an arrangement of springs that were somehow interconnected together and held each other in a state of constant simultanious tension and compression that functioned on principals found in tensegrity? Or possibly, a similar radially interconnected design, but instead built with some kind of flexible metal, possibly even some kind of memory metal, such as nitinol, which is very light and strong and is uniquely able to be deformed but when heated automatically returns back to it's original shape?

Answer 2

There have been lots of experiments with airless tires, but none have reached production for cars or bikes. The problems with all such products are:

• You're adding weight to the tire, which deteriorates the vehicle's handling.
• Tires are supposed to be flexible. Most foam products harden to an inflexible mass which makes the tire unusable. Flexible foam would quickly deteriorate under the loads that occur in a car tire.
• Even if the foam remains flexible, you'd have to fill the tire perfectly, or the uneven weight distribution would make the tire unusable.

To summarize, we use tires filled with air because we don't have a better alternative.

The only available method to mitigate puncture hassles is run-flat tires. T those work well, but they are expensive and often require special wheels.

The green slime referred to in the comments is for emergency repairs only. After a puncture you use this product to stop the leak and fill the tire so you can drive to a garage. The garage then has to replace the tire (it is no longer usable) and clean the wheel to get all the hardened foam out.

Answer 3

As you've already discovered this isn't an easy thing to accomplish!

Let's have a look at your requirements one-by-one:

Would not be too expensive

Air is cheap, I can't speak for India but here in the UK I can fill four tires with sufficient quantities of the stuff for a few pence.

One of the downsides of the airless tires that Michelin, Bridgestone and others are developing is the fact that they are noticebly more expensive than pneumatic tires.

• Would be able to support the weight of the vehicle and the rider

Not really a problem - airless tires such as Terrainarmor from Reslient Technologies are often designed for heavy loads.

• Would be easily procurable

Ahh.. here's the rub, many of the consumer-orientated airless tires aren't on the market yet as they are still in development. The Polaris Terrainarmor tires can be bought - but only in the form of the complete wheel assembly (for the Sportsman ATV) and they aren't cheap at $1049 each. The commercially available foam filling materials aren't approved for road use (other than the temp tire sealant foams - and they are for extremely limited mileage) and are aimed at tires on big off-road machinery such as Tractors. You can't just walk into your local motor factors and buy a can.

• Would not add too much weight to the tire

It's going to add weight, there's nothing you can really do to avoid that. There aren't many substances lighter than air! The most relevant comparison I could find is for the difference between using an AirFom insert vs. a conventional innertube on a bicyle - 75g per tyre. Since motorcycle or car tyres are substantially bigger than bike wheels expect that difference to climb.

• Would not compromise on traction or safety

The additional weight be considered "unsprung mass" which is likely to result in.. interesting effects on the suspension characteristics of the vehicle, possibly reducing safety in the process.

• Would be able to dissipate heat reasonably quick for a continuous commute of approx 40Km

Another problem - airless tires of the "filled with compressed plastic" type as used on heavy plant machinery have a real problem dissapating heat. The airless concepts that the major manufacturers are working on seem to do better in this regard, although there's precious little data on that aspect. A Terrainarmor-type design avoids this issue by being open-sided.

The closest you'll get would be to fill with something like TyrFil™ Flex which is a low durometer polyurethane foam - it offers better flex than a solid aperture airless tire - but it's that's relative. Despite the marketing many users have reported that it provides a very solid-feeling ride - and that's in heavy OTR vehicles like tractors! I would expect on something like a car or motorbike it's going to be basically solid. And while you might never get a puncture or blowout you are going to have damage done to the vehicle from the transmitted shocks, not to mention it will be unbearably uncomfortable!

So basically as technology currently stands the answer is a resounding "No" - there's nothing you can just fill your regular tires with that meets your requirements. It won't be long before airless tires become available for consumer vehicles though, but expect them to be expensive and only available for limited applications for quite a few years yet.