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Inflatable Tyres - Why?

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I can understand why putting pressurised air into tyres was a good idea when they were invented but why do we still use this technique.

I suppose that when they were invented rubber was very hard and the only way any shock absorption could be introduced would be to use air.

Nowadays though we have many different types of rubber and compressable foam that I would have thought could be used to make a tyre with the correct properties?

Any thoughts?

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When I had a bike for commuting I soon had the tyres changed to solid foam after a couple of punctures. Bike tyres are relatively narrow though and don't have to carry too much weight. I don't know how car tyres would last?

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Guest X-QUORK

How would you adjust tyre pressures without them being inflatable?

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Look at the car itself as a mode of transport.

Millions of individual vehicles going their own way. What an inefficient allocation of resources.

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Don't reinvent...

And air is cheap.

More importantly, its light. Solid/stiff tyres would need a lot more fuel to turn

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You can get mouses for dirt motorcycles essentially a hard foam. . The mouse tends to overheat and degrade.

Pressures should be adjusted for the load in your vehicle. Plus the unsprung weight of your vehihle should be minimum to improve handling

Essentially the idea was agood one so dont fix it

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When I had a bike for commuting I soon had the tyres changed to solid foam after a couple of punctures. Bike tyres are relatively narrow though and don't have to carry too much weight. I don't know how car tyres would last?

Never heard of those before. Where d'you get them from?

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Never heard of those before. Where d'you get them from?

I don't think you can anymore. They never really took off and I've not seen them about for a good few years now.

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I don't think you can anymore. They never really took off and I've not seen them about for a good few years now.

And they're not necessary either. Nowadays you can get bicycle types that are virtually unpuncturable, such as the Schwalbe Marathon tyres that I bought in Germany. I didn't get a single puncture after I started using them.

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I can understand why putting pressurised air into tyres was a good idea when they were invented but why do we still use this technique.

I suppose that when they were invented rubber was very hard and the only way any shock absorption could be introduced would be to use air.

Nowadays though we have many different types of rubber and compressable foam that I would have thought could be used to make a tyre with the correct properties?

Any thoughts?

Actually the problem with rubber is that it's very soft - the process of vulcanization is what makes it usable.

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Don't reinvent...

And air is cheap.

Defeatist. Nothing would ever get improved without re evaluation and redesign of products.

Air may be cheap but it also escapes when a hole is made in the tyre.

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The 'shock absorber' for the mass of the vehicle is the sprng and shock absorber in the suspension. The tyre is effectively the shock absorber for the mass of wheel. If it were not air pressure providing compliance, it would have to be some sort of mechanical 'spring', adding weight.

As a point of interest, liquids are not compressible, so air could not be replaced with a liquid, in case anyone is pondering that solution (pun intended).

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The 'shock absorber' for the mass of the vehicle is the sprng and shock absorber in the suspension. The tyre is effectively the shock absorber for the mass of wheel. If it were not air pressure providing compliance, it would have to be some sort of mechanical 'spring', adding weight.

As a point of interest, liquids are not compressible, so air could not be replaced with a liquid, in case anyone is pondering that solution (pun intended).

Is that correct? What about hydraulic rams - don't they get hot?

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Is that correct? What about hydraulic rams - don't they get hot?

OK, to be precise, liquids are not compressible for the purposes of shock absorbance in a tyre. For example, for each atmosphere increase in pressure, the volume of water decreases less than 50 parts per million. Filling a tyre with liquid would effectively make it solid.

I was merely anticipating someone proposing filling a tyre with liquid to slow down the effects of a puncture.

Edit to add: That is why liquids are used in hydraulic rams.

Edit to add: Liquids are used in 'shock absorbers' of a vehicle (more correctly called dampers) but they require a spring to temporarily store the energy while it is dissipated.

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More importantly, its light. Solid/stiff tyres would need a lot more fuel to turn

I think this is the key, certainly for high speed applications. A heavier tyre would have a greater moment of inertia, so more fuel needed to get it up to a speed in a given time; also, more effort needed to stop it, so better brakes would be needed.

Those costs every day would wipe out the cost of repairing the odd puncture..unless you're really unlucky.

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OK, to be precise, liquids are not compressible for the purposes of shock absorbance in a tyre. For example, for each atmosphere increase in pressure, the volume of water decreases less than 50 parts per million. Filling a tyre with liquid would effectively make it solid.

I was merely anticipating someone proposing filling a tyre with liquid to slow down the effects of a puncture.

Edit to add: That is why liquids are used in hydraulic rams.

Edit to add: Liquids are used in 'shock absorbers' of a vehicle (more correctly called dampers) but they require a spring to temporarily store the energy while it is dissipated.

So am I right in thinking that a hydraulic ram would get marginally hotter when compressed - but the amount of heat is tiny as the volume decrease is negligible?

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So am I right in thinking that a hydraulic ram would get marginally hotter when compressed - but the amount of heat is tiny as the volume decrease is negligible?

Sort of - although the volume change may be small, it may need a lot of energy to increase the pressure. If you are comparing with a gas, however, there is a lot more mass in a given volume of liquid, which would require much more energy to heat it up.

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OK, to be precise, liquids are not compressible for the purposes of shock absorbance in a tyre. For example, for each atmosphere increase in pressure, the volume of water decreases less than 50 parts per million. Filling a tyre with liquid would effectively make it solid.

I was merely anticipating someone proposing filling a tyre with liquid to slow down the effects of a puncture.

Edit to add: That is why liquids are used in hydraulic rams.

Edit to add: Liquids are used in 'shock absorbers' of a vehicle (more correctly called dampers) but they require a spring to temporarily store the energy while it is dissipated.

These explanations are wrong.

Hydraulic rams work on the principle of conservation of momentum and the incompressibility of water.

Shock absorbers absorb shocks using gas compression and fluid viscosity. Again, no compressibility of fluid is required.

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The 'Tweel' video is impressive, but I guess that compressed air is still the most effective way of primary cushioning. A lot of lorries, buses and coaches have air suspension nowadays, in place of steel springs, and this gives a much smoother ride. So air must have something going for it!

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The 'Tweel' video is impressive, but I guess that compressed air is still the most effective way of primary cushioning. A lot of lorries, buses and coaches have air suspension nowadays, in place of steel springs, and this gives a much smoother ride. So air must have something going for it!

Same as front suspension on mountain bikes. Air is the #1 option. Never tried it myself so will have to rely on experts views. It is better apparently.

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  • 259 Brexit, House prices and Summer 2020

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