They aren't airless, they just don't depend on compressed gas.
Technically correct
Michelin Airless
131–140 of 316 posts
Re: Michelin Airless
#132Former automotive engineer chiming in. "Tweels" have been around a long time, but have always failed in terms of "NVH" (noise, vibration, harshness). Michelin is claiming that this generation of tweels are appropriate for passenger cars, which means that they think they've solved the NVH problem. They seem to be marketing these alongside EVs, I wonder if they're only really intended for lighter, compact-style cars. (…
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Re: Michelin Airless
#133Earlier quoted context omitted.
A pebble shooting out of the upper side of a tire of a car at 250 km/h is probably as bad as a bullet. Probably worse.
So about the same as a pebble that gets stuck in treads or kicked up by same? Definitely better than a bullet though just by nature of lower speed, what it's made of and because of its poor aerodynamics.
These spokes seem to be able to fit larger pebbles that may be launched from the side of the wheel and escape the wheel well.
Re: Michelin Airless
#134Earlier quoted context omitted.
They may be for real world usage, you dont want rocks or sticks getting inside
Absolutely, my point was that if you can remove them for this sort of demo, then if they get damaged by a pothole then it's probably easy to replace them.
The demo tires shown here don't have "removable" sidewalls. They were manufactured without them. The production tires will be one piece, like normal tires.
Re: Michelin Airless
#135Earlier quoted context omitted.
Maybe the noise they generate is good for EVs which are dangerously quiet for pedestrians?
Some EVs have mandatory sound emitters to not be fully silent (and thus dangerous). I thought it was weird harmonics from the synRM engine but it's synthetic and enforced by regulations.
Hybrids as well. The Toyota Prius has had this at low velocities since before EV cars were mass produced (I believe Toyota uses a speaker that makes a sort of sci fi sound). It is a legal requirement to generate a minimum amount of noise to sell a car in some countries.
Re: Michelin Airless
#136I wonder if the rubber structural spokes could be shaped to pull air from the underside of the vehicle (tire rotation would be slightly more complicated) to increase stability at higher speeds.
Or cooling. There also might not be expansion with increase temperature?
The wheels themselves could pull air through the brake disks, but their rotation and the shape of ventilated disks already help with that.
I think I'll need to instrument my car. If something like this works, it'll seem from the inside the gets heavier the faster it goes in addition to what clever airfoils and aerodynamic design already does.
Re: Michelin Airless
#137Previous related thread here (about one month ago): https://news.ycombinator.com/item?id=28537549
Thanks. Second comment:
"""
I am an engineer working in the tire industry (throwaway is needed here). The Michelin "Tweel" IP was actually acquired when Michelin bought BF Goodrich 31 years ago. Goodrich developed the concept as a replacement for compact spare tires, doing the initial R&D in the 1980s. Every 3--5 years Michelin has a press release like this, and the technology is always 3--5 years away from release. Currently the US DOT and it's equivalents abroad are still in the rulemaking phase regarding airfree technologies, so there's that, too.
"""
Re: Michelin Airless
#138They aren't airless, they just don't depend on compressed gas.
By that definition, almost nothing but the vacuum of space is airless. Even a galvanized rubber hockey puck is going to have some amount of air in it.
Airless in this case means that they don't use pressurized air for rigidity, and therefore they do not need to be engineered to maintain air pressure, thereby reducing material input, and removing a major failure mode.
They are wheel-shaped springs.
Re: Michelin Airless
#139Earlier quoted context omitted.
Have you ever been driving when a tire blew out at high speed? It's extremely dangerous not only for the driver but all the nearby cars. This is a tradeoff between environmental concerns and safety, as are most safety features on a car. We could make a car that gets insanely good milage and has little raw material, but it would be terribly unsafe.
> Have you ever been driving when a tire blew out at high speed? It's extremely dangerous not only for the driver but all the nearby cars. Have you? Your characterization of the experience makes me think you have not. I have had two rear and one front blowout. Blowouts are just flat tires that have a loud intro before the typical "driving on flat tire" music. None of them were any more eventful than a normal flat tir…
I have. Front tire blew out, caused the car to swerve uncontrollably to the right. Luckily no one was there an I knew not to slam on the brakes but to downshift instead.
But yes, in many cases it just drags the car. None the less, it can cause huge issues.
Re: Michelin Airless
#140Earlier quoted context omitted.
Other comments here say that production tires will have sidewalls to protect the spokes and keep out rocks. If so, I'm a bit disappointed since I like the look of the spokes. Regarding catastrophic collision with sharp edge, I think these tires will be susceptible as well. If it's enough of a bump to "bottom out", it's going to dent the rim. Also, your comment about potholes reminded me of a time that I was driving w…
> My friend was driving and looked a the flat front tire and said "I'm glad I have a spare". I look at the flat back tire and said "Unless you have two, we're still going to need assistance. I did this one time. Ran over a pothole and bottomed out. As I'm replacing my front tire I look to my rear tire and see that it's also flat. That wasn't even the cherry on top. At that point I had my front wheel off and tried put…
Same situation. I usually pride myself on having good situational awareness, but something about the shock of suddenly having a flat on a major highway took it out of me. I replaced my front right tire, pulled back into the slow lane, only to finally realize my back right tire had also been blown out. I called roadside assistance, left the car there, and Uber'd home.
That was a rough day.