The End Of The Pneumatic Tire??

Caddyman

While I can see where the Military would be interested in this, it seems Michelin Tire is working on a version of these solid rubber tire/wheels for the civilian market...In this system, the wheels become flexible enough to absorb impacts...But a lot of questions remain, beginning with cost....

http://www.resilienttech.com/resilient-develops-tougher-tire-for-army

http://auto.howstuffworks.com/tweel-airless-tire.htm

jtsanders

Apparently the Tweel vibrates too much at highway speeds to be sold in mass market applications. It was first announced in 2006, and hasn't reached us yet. I consider it vaporware at this point.

dagosa

The End Of The Pneumatic Tire? "in the works" for as long as I can remember. Nothing beats air. Everything else adds to un-sprung weight and not as adjustable. I didn't know frequent flats were that big a deal if you don't rob banks or run over land mines. Can you just imagine how sensitive to vibration it must be with all those dirt, mud, snow collecting cavities. Talk about a heavy tire after driving through snow. Put a cover over it..you might as well fill it with air....low speed street patrol only in high gun ownership areas like ....

ken green

I had sponge rubber tubes in my Schwinn 10 speed.
Made me wonder...why not cars ?

circuitsmith

First, a pneumatic tire uses all of its air for cushioning when rolling over road irregularities,
Airless tires use only the material that's under load, so the ride will be harsher.

Second, friction losses in expanding and compressing air are extremely low,
far lower then flexing any solid material, so rolling resistance will always be lower, relative to ride harshness.

dagosa

I wonder too how much the ride will be affected by cold weather. The entire air mass pretty much changes temperature uniformly in a pneumatic tire. I doubt that's the case with poly spokes. And, if a rock gets stuck in one of the cavities and you go 80 mph,,what would the survival chances be ?

Caddyman

I think Mr. Sanders has it..They are just not practical for everyday driving...Too much downside, very little upside..

dagosa

I can see it comming into use for specialized use, like off roading. Gradually , in some form it may evolve into something as cheap as air.....But I'm neither holding my breath or looking forward to it. I would rather see better integration standards with mp3 players. :=)

mleich

Looks like a great idea for a lawn tractor or wheelbarrow application. Maybe for a "Bobcat" style skid-steer or other similar construction equipment?

I don't see it being practical on higher speed passenger vehicles.

jtsanders

Lawn tractors need extra weight as low as possible to lower the center of gravity. That prevents tipping of hills. I guess that the manufacturer would add weight ; maybe at the hub.

dagosa

I would like a solid tire of substantial weight on tractors. Though I have never had a problem with The liquid calcium mixture in the rear tires, something else would be appealing.

Caddyman

The old tractors used spoked steel wheels with NO tires..It would be fairly simple to add a rubber tire vulcanized directly to the wheel..

chunkyazian

Driving around LA for a few years, I've seen quite a bit of Excursions and Suburbans with huge shiny chrome rims wrapped around 10-series rubber bands. Maybe they are onto something?

"Second, friction losses in expanding and compressing air are extremely low,
far lower then flexing any solid material, so rolling resistance will always be lower, relative to ride harshness."

That is NOT how rolling resistance work. Flexing causes a temporary flat spots on the outer diameter of the wheels. The distance from the axle's center to the edge of the flat spots causes a resisting torque that the propulsion has to overcome. Train wheels flexes a lot less, hence they have greater efficiency than truck tires.

dagosa

The problem with solid spoked wheels on tractors with just rubber added to the wheel is the total lack of suspension in most tractors. The tractor would be severely limited in operating speed and the operator would be severely limited in the time he could operate the equipment without being bounced to death inside the cab. I wouldn't relish the thought of having to wear a mouthpiece and helmet, just to do a little landscaping.
In the case of a car, it would put a lot of demand on the suspension system.

circuitsmith

"Flexing causes a temporary flat spots on the outer diameter of the wheels."

With pneumatic tires the only solid material that gets flexed is the thin outer skin.
With airless tires there's much more "stuff" getting flexed (enough material to support the weight of the vehicle), and therefore more loss to friction.

the same mountainbike

The military also has a self'sealing tire that can be shot up and heal its own bullet holes. I saw a PBS special on this recently.

But realize that all these technologies come with tradeoffs. When you're invading a foreign country with no roads, the ability to self-heal is far more important than ride, handling, mileage, and even cost. A flat is no big deal in a POV on a highway in the states. In a convoy in a war zone it can mean life or death, or success or failure of a mission.

The conventional tire actually works pretty doggoned well for the extreme variaty of conditions it has to operat under. And flats in modern tires are really pretty rare, as long as they're not subjected to neglect or abuse. Or drive until the cords show.

Caddyman

Cost will kill this idea....and I forgot that farm tractors depend on the tire flex for ALL their suspension..

This is just not going to happen...

jtsanders

"Driving around LA for a few years, I've seen quite a bit of Excursions and Suburbans with huge shiny chrome rims wrapped around 10-series rubber bands."

Remember that House if Dubs a visitor mentioned recently? There's an early '70s Impala on the lot most days that looks great - except that it's on these huge rims with the same rubber bands. Those wheels must be well over 20". It almost needs a step bar the door sill is so high. I'm sure the owner loves them. Everyone has their own aesthetics.

the same mountainbike

Amen.

One other new fad seems to be to mount tires on rims too wide for them, giving them a "hot wheels" look. I've seen some kids around here do that.