Tire / Wheel Mods?

[NeilBlanchard]

Hello,

I'm wondering is anyone has thought about things like filling tires with FOAM rather than with air? At the very least, this would reduce/eliminate the need to ever re-inflate, and you could not get a flat; by definition. And, I guessing that this would minimize the rolling resistance, too.

[Edit: I want this to minimize rolling resistance with conventional tires and steel wheels. I think that new car designs should incorporate rigid wheels and tires -- and have all the suspension function in the suspension and use the hydraulics/pneumatic of the shocks and springs to charge the battery.]

What do you think? Do you want to try it? What sort of foam would you use, and how would you get it all around the tire?

Please post your thoughts.

[Piwoslaw]

First things that come to mind:
1) More rotational mass than air.
2) Less comfort.
3) Pain to change tires.
4) After time and many large temperature swings, foam may start to crumble.

[basjoos]

Your local tire shop will love you. Now they can add foam to fix-a-flat as things they hate seeing in tires they are changing. That aside, I think any foam you try will permanently flatten with use and any, such as a dense foam rubber, that are stiff enough to hold their shape for a period of time are going to add a lot of weight to the tire. The advantage of air is that, as long as the psi is maintained, it will always return to its original shape when released.

[TomO]

Michelin's Tweel

It's great for:

'Cause you can just hose of the Tweel if it gets mud-packed or snow-packed, not to mention it's low speed so vibrations due to imbalance are not an issue.

But they're still working on the logistics of keeping the Tweel clean and debris free for snow and mud for automotive use (read: rubber skirt that will cover the spokes)

[NeilBlanchard]

Hi,

Originally Posted by Piwoslaw

First things that come to mind:
1) More rotational mass than air.
2) Less comfort.
3) Pain to change tires.
4) After time and many large temperature swings, foam may start to crumble.

1) Yes, that's true, but I think it would be maybe a pound or less?

2) Again, true, but (eventually) the spring rates and dampening could be adjusted to compensate.

3) Yes, but if the rolling resistance could be cut to a fraction of what it is using air pressure, then you probably would save a lot of fuel, and it be worth it. Besides, I am thinking of this as an experiment.

4) Right -- that is why I was wondering about what kinds of foam that would be less likely to NOT break down. I know that foam used in stress skin structural panels on buildings are amazingly strong and rigid. A rigid tire would not heat up very much -- and it would roll very, very well, I think!

As for the TWEEL -- it is designed to replace standard tires and to have the same kind of flexing. Which is exactly what I'm trying to eliminate.

[DC2many]

Originally Posted by TomO

Michelin's Tweel

It's great for:

'Cause you can just hose of the Tweel if it gets mud-packed or snow-packed, not to mention it's low speed so vibrations due to imbalance are not an issue.

But they're still working on the logistics of keeping the Tweel clean and debris free for snow and mud for automotive use (read: rubber skirt that will cover the spokes)

lmao those tires look so gross!!

anyways, you can try this experiment yourself but they do have some fillers in place of air for bike tires i think.

to have it safe for use w/ minimal problems on a car is going to be some hard work

[micondie]

Off road construction equipment tires are regularly filled with a foam to eliminate the chance of flat tires (Imagine trying to fix one of those flats!!!!!!!!)Check with a local tire store that handles those large tires.

[NeilBlanchard]

Hi,

I found this:

Bicycle Tires Guaranteed to Never Go Flat

They appear to make foam inserts for some types of tires.

[woodsmith]

Solid tyres are fine for slow moving equipment. High speed tyres wouldn't cope with being solid due to the heating that happens from the distortion and deflection of the sidewalls and the contact patch in coping with the rolling and side forces acting on the tyre.

If you took a car tyre and filled it with anything solid then running it at speed will cause a large amount of heat to build up. To get an idea of how much heat the tyre has to deal with do a long fast run in the car and then immediately stop and feel the rubber. It is quite warm and yet shedding heat as best it can, quite efficiently, being air filled.

The heat comes from the friction of the rubber with the road surface, the flexing of the rubber and from the compression of the air inside. The air is being compressed by the flat spot that travels around the tread of the tyre as the tyre rolls The compression is continuous around the tyre and sends a wave of compressed air around the inside of the tyre. The air movement inside allows the heat generated by the compression wave and from the rubber to be dissipated to the rest of the tyre.

If the tyre was solid then the heat would not be able to dissipate as readily and so the inside of the tyre would oveheat very quickly and then deform. This would lead to instability within the tyre, flat spots and lumps forming and then melting of the tyre core.

In the grand old days of heavy haulage when solid rubber tyres were used the road speed had to be kept very low, 1-5mph depending on load. Over speed those tyres and the solid rubber just melts inside.
The same would happen in a car tyre, just at less load and higher speed.

[Bicycle Bob]

The flat spot as a tire rolls will stir the air a bit, but it does not work as a compressor. It is like a piston with no cylinder. The average volume inside the tire is constant.
The promising work on solid tires has focussed on urethane. It comes closest to the low hysterisis of air, but several serious, well-funded attempts have not gotten it to market.