Discussion thread for: Michelin "Tweel"

[vtec-e]

Those wheel nuts are going all Ben Hur on you!

[Christ]

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.

[Frank Lee]

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.

[Christ]

Originally Posted by Frank Lee

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.

[Frank Lee]

Hysteresis is non directional... ?

[Christ]

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.

[Frank Lee]

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