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View Full Version : Why are rubber tires better than wood or metal?



larocca
05-18-2010, 06:46 AM
It's a valid research question. I'm stretching myself with the new novel, big time.

Oh, and I'm thinking of bicycles as opposed to motor vehicles here. Wagons pulled by animals too, but on Earth they were gone before the advent of the rubber tire, so I probably don't have to care so much.

Thanks!

veinglory
05-18-2010, 06:51 AM
Reduced wear and shock absorption. If the wheels are solid then i hope they have sprung suspension or their butts will be sore!

justAnotherWriter
05-18-2010, 07:03 AM
Many, many reasons.

1. Rubber deforms to create a larger contact patch than the size of the tire, which increases traction over uneven surfaces.
2. As veinglory said, shock absorption, which is huge. Rubber tires act as a bouncy cushion.
3. Noise. Rubber tires are much quieter.
4. Durability. Due to their shock absorbing qualities, they isolate the vehicle from vibration and shock, which prolongs its life.
5. Lifespan. Wood warps, cracks and splinters.


I'm sure others will think of more reasons.

Wayne K
05-18-2010, 07:07 AM
Weight

thothguard51
05-18-2010, 07:20 AM
You know, I know this is a serious question, but I just can't believe the answer is not obvious.

Can you imagine wood tires and having to come to an emergency stop, it would be like sanding a bowling ball. When you start forward again, the tire would have a flat spot. That is just one of the obvious answers.

Weight, durability, performance... lots of reasons.

There is also a reason tires are round and not square...

backslashbaby
05-18-2010, 09:05 AM
Metal would get crazy hot. Not so much for wagons ;) They used to be metal, too, didn't they? For wagons, I'd think comfort/not spilling things, mostly.

RobinGBrown
05-18-2010, 11:30 AM
There's a difference betweeen solid rubber and air filled rubber tires too. Solid ones are much easier to make (i.e. more likely to be made with lower tech resources) but don't give a smooth ride like air filled tires.

Don't forget that springs were invented before rubber tires in our world.

shaldna
05-18-2010, 12:06 PM
If you ever get a chance call into a folk and transport museum, explain to them what you are researching and ask if you can try a bicycle. In my experience they are super keen to help people out with this sort of thing.

Kathie Freeman
05-18-2010, 07:32 PM
Wagon wheels were generally made of wood, though many had metal banding. Old tractors had metal wheels for durability.

Nivarion
05-18-2010, 07:40 PM
one thing that jumps to mind is the spolks of the wheel would be better protected.

If you hit a large bump with a hard tire its less protected and could be broken.

Which happened often with wooden wheels. large wagon trains had to have a carpenter or smith with them that could fix the wheels well or they could end up in a lot of trouble.

Soccer Mom
05-18-2010, 07:55 PM
Seriously, if you had ever ridden in a horse-drawn carriage, you wouldn't ask. I drive donkeys and solid material wheels (such as wood or metal) give a much rougher ride, even with good suspension. There is also the issue of traction and wear and tear.

I can't imagine riding a bike with wooden wheels. My bottom hurts just thinking about it.

Stanmiller
05-19-2010, 02:25 AM
My head hurts thinking about the Mod Bunneh driving a donkey.

Michael_T
05-26-2010, 04:23 AM
As long as you're not going too fast and not going over pavement I'm sure that wooden or metal wheels would work alright. So if you had a rigged wood/metal wheel on a bike and were riding through grass, it would be fine, except if you hit a rock and splinter your wooden wheel.

Canotila
05-26-2010, 05:10 AM
I got to do a several day handcart trek through the wilderness several years ago. We had handcarts with metal wheels, and they were being pulled on dirt, rocks, and grass.

A HUGE number of wheels were broken. Usually it was just a spoke or two when going over bumps in the road (each cart had approx. 300 lbs in it, not that much when you consider that could be just two lightweight adults). A couple of wheels broke majorly. One broke off at the axle and nearly took someone's leg off as the loaded cart shoved it to the ground (this was going over a pretty large boulder). Another had so many spokes break the actual tire part finally separated and was useless. Good thing they brought extra wheels.

I think that if they had rubber tread instead of metal, there would definitely have been a lot less stress on the spokes as the carts were jouncing all over the place.

Sarpedon
05-30-2010, 05:25 AM
The answer is simple: physics.

Objects in rotation have rotational inertia, which resists forces attempting to change the angle of the rotating object (angular momentum). EG: a gyroscope, which features a rotating metal wheel where the mass is all at the rim. It is difficult to upset a gyroscope because this rotating mass resists having its angle of rotation altered.

This would not be desirable in the wheel of a vehicle: the angular momentum of the wheel would resist changes in its aspect, that is, any attempt to steer it, or brake, for that matter. For that reason, it is advantageous to have most of the mass of the wheel at the axle, and little at the edge, to minimize the angular momentum.

A wheel with a metal rim would have more mass at its edge than a rubber one, which is mostly filled with air. Thus it would have more angular momentum than an inflated tire.

Newguy1428
05-31-2010, 03:18 AM
Tanks and construction machinery do just fine with metal tracks. It depends on function. When I delivered newspapers, the old metal-rimmed, wood pinwheels did just fine. I had 400-600 lbs of Sunday papers and ran at a good clip. They had to be maintained, but I never had a breakdown.

I also remember old roller skates had metal wheels. I am sure they were just for kicks. they got nicked up so fast.

I say speed. But. I imagine I mean grip is why rubber is so dominant.

WriteKnight
05-31-2010, 06:03 PM
Form follows function. What size is the load? What NATURE is the load? What speed is the transit? What surface is the transport? Active propulsion or passive friction reduction?

Metal, Rubber, Wood, Wire Mesh - many different types of wheels still in use around the world, and across our solar system today.

Julie Worth
05-31-2010, 06:07 PM
Tanks and construction machinery do just fine with metal tracks.

Not to mention trains.

Sarpedon
05-31-2010, 11:18 PM
tanks, other tracked vehicles and trains are all vehicles that don't have to worry about turning the wheel in order to steer.

WriteKnight
05-31-2010, 11:22 PM
Lower the speed, the less important rotational inertia becomes. Also, the 'steering' wheels can be smaller than the 'tracking' or load wheels.

Sarpedon
05-31-2010, 11:53 PM
I believe they tried that, and it was something of a failure.

Drachen Jager
06-01-2010, 12:34 AM
Tanks and construction machinery do just fine with metal tracks. It depends on function. When I delivered newspapers, the old metal-rimmed, wood pinwheels did just fine. I had 400-600 lbs of Sunday papers and ran at a good clip. They had to be maintained, but I never had a breakdown.

I also remember old roller skates had metal wheels. I am sure they were just for kicks. they got nicked up so fast.

I say speed. But. I imagine I mean grip is why rubber is so dominant.

Modern tanks/APCs have rubber treads installed for travelling on roads, they only take them off when they won't be driving on hard surfaces.

Metal works fine on dirt because the dirt takes up the shock but on a hard surfaced roadway the treads get damaged too easily without the rubber pads.

Another reason to use rubber on roads is that it's much easier on the roads. Wood is fine for cobblestones or bricks but will rut dirt roads much faster than rubber. Metal will destroy nearly any kind of road surface pretty quickly.

WriteKnight
06-01-2010, 01:30 AM
Bicycle wheels front wheels are much heavier than their center hubs. Same is true for many motorbikes. "Turning" is achieved at high speeds by 'leaning' not 'turning' the wheel. At high speeds on my motorcycle, I PUSH the right handlebar to go right, not left.

Front wheels of some cycles ARE smaller than the back wheels. They've tried that. It works.

Front wheels of dragsters are smaller than the back wheels. They've tried it, it works.

Drachen Jager
06-01-2010, 09:12 AM
Front wheels on a dragster are smaller because they don't provide thrust and need to be as light and streamlined as possible.

Dragsters are not road vehicles, none of the practicalities of a regular vehicle apply.

They don't need to steer they just need to correct slightly.

WriteKnight
06-02-2010, 06:24 AM
Define 'steering' - if they don't steer correctly, the driver is dead.

You make my point - "Form follows function" - thank you for agreeing. I was merely illustrating the point that there ARE wheeled vehicles who have smaller wheels in front. This was in response to the assertion regarding why use inflated tires instead of metal ones:

. For that reason, it is advantageous to have most of the mass of the wheel at the axle, and little at the edge, to minimize the angular momentum.

WHile angular moment does affect wheels, my point was that at low speed, it's not an issue, and at HIGHER speeds, 'steering' can be affected with vary little change of angular momentum -and in point of fact, many bicycles and motorbikes DO have a greater mass at the outer rim, and have no trouble at all 'steering' by slight changes in their angular momentum.

As my earlier post states, it's a matter of many different elements - FORM FOLLOWS FUNCTION.

larocca
06-02-2010, 07:50 AM
http://www.michaeledits.com/bike.jpg

This was discovered in Alabama in the 1890s. It was built by a negro who couldn't afford to buy his own bicycle. I find the three drive gears interesting because the one on the back was wood with iron teeth.