Discussion thread for: Michelin "Tweel"
 

As the title states, I'd like to get an "at-length" discussion going to ascertain the possible benefits and downfalls of the newest product in development at Michelin's South Carolina plant: the Tweel.

So named for it's odd design, which looks like the lowest profile tire you've ever seen, on a wheel with more spokes than it should have.

If you're not yet familiar with this marvel of the automotive world, I welcome you to click on the picture below, where you will find the first 20 images in a Google Image Search for the term "Tweel".

Ok - so it's not really that new... it's actually going on three years since it started in R&D... so why haven't we seen it yet? I have a feeling we soon will...

http://servicesv2.webmichelin.com/fr...mentCode=49716

Christ -

This sounds like a thread for CapriRacer. I don't know anything specific. I first read about it here :

Car Bibles : The Wheel and Tyre Bible Page 1 of 2
CarloSW2

Ahh, a new picture, this time on a road-builder, not a road-runner. That seems sensible. I think the problems were heat, rolling resistance and noise, but it can be looked up.

Another: Nu-Teck Manufacture of Airless Puncture Proof No Flat Tires

Michelin isn't the first.

Anyway... I think airless would be great when they get them to work. Apparently it's TOO MUCH EFFORT to keep tires full of air? I see way low tires on the street every day.

From what I remember reading in a post last summer they are using this on heavy equipment where the short comings aren't noticed as much. There is a company that has taken the tweel design and modified it to a honeycomb pattern. It evens out the pressure and smooths the ride slightly. I can't remember where I read about it though; it was last semester sometime, fall '08. Was either jalopnik, treehugger, or autoblog I read it on.

Looks like you'd have fun keeping it clear of snow so it stays balanced in the winter.

yeah... not for use in canada... park with a wheel in a driveway groove and it'll be iced THROUGH by morning... I'm sure they could mix the designs and give it a flexible structurally-irrelevent sidewall just for protection from snow and squirrels getting caught in it. Although, as a summer tire in canada, it makes sense - especially with its alleged cornering ability and "cool factor".

A sidewall would also help with the "air blender" that i'm sure ecomodders will point out.

Lasting twice as long means half as many tires in the landfill, too. And since it is injection moulded isntead of many layers of belts, i'm sure it could just be shredded, melted and become new again.

Several years ago we fitted airless tires to the scrapyard bobcat. I never knew what brand they were though. Ride was rough as ****, but no more flats.

needs sidewalls so they don't chew up the air.

Dang, how many times is someone going to "discover" the Tweel and start a discussion about it? This happens on every board I'm on! :p

Hi,

I think that a composite tire/rim would be fine if it could have vanishingly low rolling resistance, good aerodynamics, and if the suspension was tuned to work with it.

As it stands now, the aero drag would be a deal killer, and the amount of sand/ice/snow that would build up on the inside would also be a deal breaker.

I think you mean Resilient Technologies out of Wausau, Wisconsin. As far as I can tell, they are for military Humvees at this point. Not sure about the downsides, but I would imagine that if your tire got shot in Iraq and these allowed you to make it back to base, they would be worth their weight in gold to you.

Yeap, that's the one. Seems like a better design, although with mud and snow pack I doubt the military cares as much; just drive the piss out of it anyways. Sand and loose dirt are about all I'd want in there. I'd bet the way the tire deflects under pressure it would loosen out anything stuck in there.

the biggest concern I see with any consumable, safety-related automotive product is consumer ignorance.

As was pointed out, there are entire cities worth of adult humans unable to wrap their brain around the concept of keeping their tires inflated. Every single day I'm behind at least one car with a tire so low it's making the car pitch to the side... and worn well enough to indicate it's been like that for weeks. Generally when I pass this moving hazard I look over and see the driver's vacuous glazed eyes... well, they have drivers' licenses too.

At least when the tire finally pops they do have to confront the fact that it needs to be replaced.

What of the tweel? Does it have a consistent/predictable/"safe"? failure point when it has outlived its usefulness or been damaged as a result of collision, abuse, or chance encounter with debris?

Yup. I had a mate call in one day with the tread gone on a front tire. I checked pressure and there was none! It was a run flat! He didn't know it was and neither did i as there was nothing written on the sidewall to that effect.
So here is a tire designed to get you home in an emergency and still people push it beyond the limits.
I think there is merit in the tweel but all the above problems need to be addressed for it to work. And i sure hope we get the option of choosing a tire with a "higher pressure" if you know what i mean. It'll be no use to us with a simulated 32 psi will it?

ollie

Depends on the R.R.

Hello,

I think you are underestimating the power of centrifugal force!

I don't think a faux sidewall for the purpose of keeping gook out is a big technical hurdle.

They wouldn't want to show such a thing in their early publicity shots because that wouldn't be at all eyecatching.

Nope, certainly ain't! I've driven from Fairbanks to Anchorage, (AK) with snow packed in my steel rims. It did not come out.

Somewhere I have a picture of snow/ice/dirty water buildup on my GP from a recent road trip. The centrifugal force created an amazing design on the rims spreading out from the lug nuts. It was like watching icicles form at 90* arcs. I'm sure you can imagine what it looked like. Anyways, it didn't fly off, it held on for about 350 miles, Denver to Northern WY. I'm sure it re-accumulated along the way, but I was watching it with my mirrors since Fort Collins, CO.

I'll see if I can find the pictures....

Okay, the thumbnail is a picture from going to Seattle, stopped at Cour De 'Alene for fuel. You can see the mild beginnings.

Here we go for the stop at Sheridan, WY:
http://lh3.ggpht.com/_dNGPTC1J5JE/R3...2/DSCN8624.JPG


Granted this is ice buildup, not snowpack. But nevertheless I still feel the buildup would create problems. A cover would solve that easily, AFTER the awesome PR pictures have been taken.

Those wheel nuts are going all Ben Hur on you!

So this got taken up pretty quickly here LOL...

My opinions on it, be them educated or purely superficial:

1. Great technology, regardless of the perceived "hard ride"... c'mon... pump your tires to 50 PSI and tell me you're going to be mad about a hard ride??
2. Rolling resistance is greatly reduced by the lack of a flexible sidewall, which means that even though the tire is "flattening" at the bottom, it's only flexing on a single axis, as opposed to the sidewall's flexion, which occurs at every possible angle in all 3 dimensions, over a larger surface area.
3. The "fan" problem. Well, adding a sidewall kinda kills the RR part... so how about making them so that they "suck" air from under the car, blasting it outward? Does that work? Would that create another aero problem?
4. Recyclable: Well, with standard tires, it's not the "can't separate materials" that makes them not a candidate for recycling... it's the fact that they're vulcanized. You can't recycle Vulcanized rubber into non-vulcanized rubber, apparently. And to make tires, you need non-vulcanized rubber. It's also just plain not cost-effective to separate all the diff materials. Chances are, the Tweel is going to be an impregnated (not fully rubber) wheel/tire.
5. Damn, that thing looks awesome moving... if you can find a video, watch it.
6. Weight is an issue... the tweel (w/o the metal wheel) alone weighs about what a standard wheel/tire does normally. Then you have to add a "special" press-fit wheel that it can ride on, which COULD save some weight over a normal rim, but the assembly still weighs more.
7. That thing still looks really cool... LOL.

1. Try something with airless tires and get back to us.
2. There are still many elements flexing in the Tweel so I wouldn't think it prudent to speculate on r.r. vs. conventional.
3. Why would adding a sidewall kill the r.r. part? It could be made much thinner/more pliant than a load supporting sidewall.
6. It is tough to come up with materials/structures that weigh less than air.

Most things that have airless tires also have solid tires, and no suspension.

This (in car form) isn't even close to that.

Forklift tires, are press-fit to steel donuts. They're vulcanized rubber sheets themselves, wrapped around a steel drum, then press/heat formed.

large equipment airless tires are generally about the same, except often with split rims instead of press-fit rims. They also have no give, other than the 70D rubber's propensity to "squish" slightly.

The Tweel is a whole different ballgame, in that it actually DOES flex, quite significantly. Yes, the ride is harder, but I cant imagine it being much harder than the ride on a set of 215/35ZR18 tires with 60PSI in them on a car that only weighs 1600lbs, and I don't really consider that harsh either.



As far as RR goes, maybe I could be incorrect about having a guaranteed better RR, but intuitively, it should. I say this b/c even though there are more flexing components, the flexion is all at a 90* angle to the direction of motion, or "radial flexion". Compared to a standard tires which has flexion in every direction on all 3 axes.

Hysteresis is non directional... ?

Point - try folding something sturdy like rubber in one direction at a time. Easy, right? You can even roll it around in one direction, just the same way that forward loading would move a heavy rubber band, with relatively little effort.

Now try folding it in xA=pi*speed of light^3(3*eleventybillion+overninethousandddddd!) directions at the same time.

A little harder?


Please forgive the careless exaggeration, but I'm not sure of the proper formula to describe frictional losses due to flexion.

Once again, intuitively.

IF someone can show me how this is incorrect, I'd be more than happy to personally edit my beliefs.

I'll wait for some r.r. data.