Why are car tyres filled with air and not solid rubber?

Generally, as Mr Dunlop knew, this allows for alterations in air pressure for different vehicles and bikes, so that the optimum can be achieved for different circumstances.

Obviously, racing cars, different types of road cars, road bikes, mountain bikes, etc, have to have the right pressure for the job. This provides for increased comfort, especially over rough surfaces, and for increased safety.

Many early vehicles did indeed have solid rubber tyres (and even metal and wood on ancient carriages). They had the benefit of not having punctures! Oddly, the wear and tear was greater than for air-inflated tyres. Incorrectly inflated tyres also have greater wear.

There are still specialist means of transport with solid tyres, even today. Some kiddies' bikes have them, as do some land-speed record 'cars'. These are normally suitable only for smooth surfaces; otherwise, the ride would be unbearable and damage would soon occur.

I have refrained from giving sources, as there are thousands of histories and descriptions available, including on the Internet. I hope that the basic information helps.

two immediate answers, weight and comfort

Solid rubber would add a lot of unsprung weight, thats weight that isnt sitting on the springs

The solid rubber tyres would be a bit like a squishy brick, not very good, and also they would get damn hot on bumpy roads. You can see some radical wheel tyre combos in the past, Volvo made an aluminium rim that just had a thin rubber tread on it, really light, but prone to noise and comfort problems

Some really high pressure tyres have nitrogen in, and once a long time ago the RAmChargers drag team weighed their car in with water filled tyres, they were caught switching back before the race

I think this every time i get a puncture on my ride-on mower.

I have a plan this year to experiment with strips of rubber inside the tyre. All i need is a spare day to mess about.

cars i can understand - they need balance and there is a lot of safety issues.

I can see why they cannot be SOLID. But what about the compromise ? What about tyres with sealed air pockets so they run even when one pocket is punctures. Or a honeycomb structure that doesn't need any air pressure but relyies on flexible rubber supporting internal pillars ?

I know, we now have "run flats" but did it really take 100 years to get to that ?

Sometimes i think the tyre designers are asleep on the job.

As fr my mower not having this, its unforgivable. For the sake of a £5 tyre they give me 10 years of grief with punctures.

Most people are answering weight and comfort... Actually, the biggest problem with solid rubber tires is heat buildup.

Back in the late 1970's The US Air Force bought some light armored vehicles for use as convoy escort vehicles. They had solid foam filled tires, to make them "bulletproof" The problem was that if the tucks ran on the highway for more than an hour, the foam inside the tires would heat up and start to melt, and the tire would go off-balance and destroy itself.

We had to replace all of the foam filled tires and wheels with standard truck wheels and tires.

I agree with everyone else here, the ride would be awfully rough on solid rubber tires and they would no doubt cost a lot more also as there would be many many times as much rubber involved in making a solid rubber tire.

Well I just had a new set of tyres put on and the fitting centre filled them with pure nitrogen as this improves wear and gives you more miles to the gallon as they don't heat up so much and you don't loose so much pressure like air.

Mind you the air has 80% nitrogen in it.

The "solid" tyre that Rajan K was talking about is probably a Michelin Tweel - it's a tyre and wheel in one, hence the silly name - although it's not really solid; take a look at this video;

http://www.youtube.com/watch?v=v7gANJWRWIs

If you'd ever ridden a bike with solid tyres, you'd know it hurts. A pneumatic tyre (invented by Mr Dunlop) absorbs far more bumps than a solid tyre and also means you use less fuel.

at one time tires were solid rubber but the ride was so bad that they started filling it with air, if your worried about flats get run flat tires but you have to have a TPMS on your car, they are coming out with a new tire that will never get flat, i searched but cant find them sorry

They are like this because the help the suspension in the car.

if it wass all made of rubber you would feel every hole and

bumb in the road.This is why they fill it with air

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