Wouldnt a solid rubber tire do the same job with no risk of punctures?
In: 296
Nope.
In order to think through this take the current solution, your proposed solution, and write out some pros and cons and relative weight.
Punctures aren’t the end of the world. And people can go years without punctures.
The increased weight alone of solid rubber over air would come into play all the time. Similar for the cost of that extra material. And that’s even before you get into less obvious things like heat or ride quality.
That being said, there have been attempts at airless tires. A Google search for airless tire will bring up information that someone spent more time explaining not just what we effort some random people spare for a fresh comment on Reddit.
Solid rubber tires have their purpose, but it’s not on cars.
Yes, solid rubber tires would be more durable, but it has it’s drawbacks. Air filled tires are designed to compress and flex to absorb bumps and grip better. Also, you need a different amount of tire flex based on your needs. If you’re just driving on the highway, use what the door panel recommends. If you are running off road, decrease the PSI for better traction.
Forklifts use solid rubber tires though because they don’t need as much grip compared to a car, the move slowly, and generally are used on flat surfaces. You would have a real bad time if you hit a pothole at 65 mph with solid rubber tires.
Also, as others have mentioned, solid rubber tires would be really heavy. Unsprung mass is a pretty big factor in vehicle performance. Not only are you CARRYING that much more weight, but the engine has to work harder to TURN that heavy mass. AKA less fuel economy/worse performance.
2 Reasons:
1) Shock absorption. By filling a thin layer of rubber with air, the skin of the tire becomes a shock absorber on its own. As the tire recieves an impact, it flexs in response to the pressure change within. This makes not only for a smoother ride but makes components last longer
2) Weight. You want a vehicle to be able to quickly accelerate/decelerate. Pick up a tire, it’s already fairly heavy as is when it’s just a thin skin of rubber. Imagine FILLING that thing with rubber and imagine how HEAVY that would be. Now, imagine trying to start/stop that weight rolling. It would require a ton of force to start and be hell to stop.
1. Costs more as you are using a lot more rubber to make the tire.
2. Much heavier. 20lbs for a single air filled tire, 80lbs+ for a solid one. This means shipping costs are higher and wear on the vehicle is higher due to needing to move around more weight. An extra 320lbs on the vehicle for it’s lifetime is quite significant.
3. Air filled tires work like a cushion when hitting bumps, so a smoother ride. Hitting a pothole at speed might blowout a air tire, but it would likely outright break the suspension/mounts of the vehicle instead on a solid tire.
4. The rims would either need to be part of the tire or use a different design type like a split rim in order to mount/unmount the tire.
Pneumatic tires are superior because they allow the rims to be much lighter, which cause the car to have better performance and use less gas, due to the gyroscopic effect. The reason is that when you go over a bump with a pneumatic tire, the compression is distributed over the entire rim, pushing down on the rim from all sides equally. For a solid tire, when you go over a bump, the entire force of that bump pushes down on the rim at that location, and will cause the rim, unless it is dramatically heavier, to fail.
You would need about triple the amount of springs etc. Rubber is quite dense so your wheels would be wicked heavy, also you would be bending wheels left and right.
Solid tyres have been used and up until a few decades ago I had solid tyres on a trike I had (I was small kid). They don’t retain tread any better and they give a worse ride. For use in anything larger they’d use excessive rubber, be more expensive to buy, be heavier and use more fuel too. The cheapest option is using air or nitrogen filled tyres..
Off topic sort of..
But why not concrete tires and rubber roads?
Air pressure is easily adjustable. Hardness of rubber is not.
In addition to being way too much unsprung mass, the rubber would have to be VERY soft to provide a comfortable ride, and would therefore not last very long at all
A great in-person experiment to learn about this requires a solid ball like a medicine ball, an air filled ball like a kickball or yoga ball, and a friend with a baseball bat.
Hold the solid ball and hit it with the bat, then hold the air-filled ball and hit it with the bat and compare how your arms feel afterwards.
Both types of tires have their purposes, but the air filled ones feel much more pleasant to interact with when you meet things like bumpy roads or baseball bats.
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