Re-designing the Tires?

[HydroJim]

I'm sure some of you may have seen this before, but I hope these get put into production soon. Seems like a very good idea to me.
Their recent tests show a 50% better coasting! that would be great for fuel economy.

http://www.youtube.com/watch?v=OGvRn...eature=related

[cfg83]

HydroJim -

I haven't seen this one. I thought it was going to be the all-rubber airless tire. It's very techy cool, so I hope it pans out.

CarloSW2

[Frank Lee]

There've been tweels and other airless designs for decades. I would have liked more real footage and less computer generated animation. I noticed that on the one glimpse of real footage, they only had their invention on the right rear. I'm having a hard time imagining all those bolts transmitting torque, especially braking torque, and not wearing out all sloppy in very short order. The Tweel doesn't have sliding moving parts like that, only flexy elements. BUT, it would be nice to see them make something like this work. God knows keeping tires aired up is too taxing for today's motorist.

[HydroJim]

yeah, michelin had one too. Fast Cool Cars - Airless tires - The Tweel - Michelin

I wonder what is keeping these things from coming to market. I'd imagine it's the cost of equipping tire shops with the equipment and knowledge to mount and maintain these tires. and, the fact that the tread is supposed to last 2-3 times as long. If anything, they are even cheaper to manufacture because the tire is just a solid piece of rubber.

But, if I'm not mistaken, the radial tire took about 2 decades to become accepted so maybe the case will be the same for these tires.

Unless their is some hidden negative that we haven't learned of yet, there is no reason that these tires shouldn't be being sold right now.

[brucepick]

I found this link, from April 2010: Reinventing the Wheel: a Guide to Michelin’s Airless Tire - autoevolution

Please do have a look, this is a fairly informative article. It includes this:
"...One of its biggest flaws is vibration. Above 50 mph, the Tweel vibrates considerably, thus generating noise and heat. A fast moving Tweel is reportedly unpleasantly loud. Long distance driving at high speeds generates more heat than Michelin engineers would like. That’s why, for the moment, the first applications of the Tweel are in low-speed vehicles, such as construction vehicles. ..."

I thought I saw an announcement that the tire was to be released this fall (2011). But a google search turned up nothing on that.

[NeilBlanchard]

The main idea they have is great. I would want to see how a more rigid version of this wheel would work with a regenerative shock absorber, like from Levant Power:

Levant Power Corp.

I got to meet with two of the Levant folks last week (at the MIT "Energy Night") and they would need to scale the shock down for a lower weight vehicle, and tune it for more frequent and smaller strokes that having a wheel like the ERW would bring.

The other major hurdle for ERW is aerodynamics. Having a open wheel will really churn the air and cause a lot of drag. Also, gravel and snow and rain will be flung by this wheel, and they can get inside the rim and throw it out of balance.

I would *love* to use these wheels on CarBEN EV5!

[HydroJim]

I did not know about the noise at highway speeds for the michelins. That is definitely a big issue. I noticed on the ERW wheels, they used a rubber membrane to reduce vibration.

Skip to 2:50 to see how they solved their vibration problem.

http://www.youtube.com/watch?v=iOSAQ...eature=related

I believe the aerodynamics can easily be fixed with smooth wheel covers. and the portion around the edge where the space will change with each bump, can be covered with thin rubber.

If what ERW says it true, than michelin will not be able to sell their tweel because ERW has the patents. It's too bad because michelin is the one with all the money to get a product to market.

[cfg83]

HydroJim -

I agree that wheel covers would help the aero. The extra metal (convector) in place of the tire (insulator) would also help in cooling the disk brakes, yes?!?!?!?

It's definitely cool. As Frank says, it seems like there are all these multiple points of failure. The good side is that it appears (to me) that it would fail gracefully, i.e. the bolt connections would degrade to the point where they as a problem would be obvious. The (TBD) bad side is how durable it is. Would it last say 60K miles? Or would the replacement interval be split up where the metal portions would last maybe 200K miles with the rubber parts being replaced maybe every 20K miles?!?!?!?

Me not know,

CarloSW2

[HydroJim]

The article says the tires last 2-3 times as long as normal. So I'm guessing about 100,000 miles? as far for the metal portions, I have no idea. I'd imagine the intervals would be similar to suspension intervals which are very long.

It sounds like ERW beat Michelin to that patents and that is the only thing keeping this things from going into production. I'm sure there are other issues, but I really wish I could try a pair.

[Ladogaboy]

I'm still wondering whether this belongs in the Unicorn Corral. In my experience, any increase in efficiency will result in a commensurate increase in noise, vibration, and harshness (NVH). Likewise, a reduction will in NVH will result in a decrease in efficiency. Typically, the areas where efficiency are compromised the most are those areas that affect consumer conscience (e.g., aesthetics and ride comfort).

This is most evident in the performance car sector, where drivers are constantly looking for ways to more efficiently transfer power. Those modifications almost always result in a less driver/passenger friendly vehicle. Many performance car enthusiasts lament modifying their cars after a point, because those cars are no longer enjoyable (even for an enthusiast) to drive daily.

Now, taking that and looking at these tires: What I see is mechanics similar to under-inflated tires. Do a side-by-side comparison of how an under-inflated tire looks as it drives over an obstacle (like the board in their video). It molds to the shape of the board and then rebounds. What they're claiming to be a transfer of absorbed energy to forward movement looks more like lost energy to me. I'm sure that the ride quality will be much improved, but I have my doubts about any efficiency gains.