Michelin has been marketing their "Tweel" (http://www.michelintweel.com/) product for industrial applications for a while, and I've read a couple of articles about their trials of the Tweel on passenger vehicles. I suppose that the challenges of higher speed applications have prevented that product from appearing.
If they can get the requisite approvals planes seem to be an ideal application of these, as burst tyres upon landing or takeoff are actually rather frequent and the shrapnel can cause extra damage... sometimes leading to catastrophic results:
Something I always wonder about is the mass. Airless tires have a lot more mass around their edges than pneumatic ones do and so at higher RPMs would seem to put more stress on both the axle and the wheel, especially when turning. That seems like a really hard problem which gas solved really well.
There are lots of ugly problems with airless tires; another beyond the ones you mention is that servicing the wheel gets more difficult. A lot of Bobcats shipped with foam filled tires and you virtually could not separate wheel and tire without chipping the tire away. These wheels + tires were also harder to get on and off because not the weight; on a road vehicle I'd imagine the potential increase in weight will also make balancing difficult to impossible.
The pneumatic tire is an awesome invention. They have the ability to cancel out imperfections in the road surface over a wide range of frequencies and amplitudes. Bicycles have traditionally used no other type of suspension.
To make a non-pneumatic tire you have to invent something equally as awesome. Normally you end up with something that produces a very rough ride.
A rough ride is the least of your problems. In a powered vehicle, the primary purpose of suspension is to keep you in contact with the road. If you're not in contact with the road, you're not in control; braking, steering and acceleration don't do anything if they can't react against the surface.
> The series of “rigorous tests” that the company is putting its tires through are meant to prove their durability, hardness (efficiency), stability, ability to take high-speed turns (slalom), and ability to maintain their integrity at high speeds (up to 130 kilometers per hour).
That's only 80 MPH. I'm interested in the no flats and potential fuel savings but I'd want to be able to travel at freeway speeds on long trips with them too without having to change out tires.
In many countries, the law requires that tires must be specified, and fitted, to exceed the maximum speed of the vehicle they are mounted on, with regards to their speed rating code (except for "temporary-use" spare tires).
I see it as a safety factor - the speed ratings of most common tires (S or T, 180 or 190 km/h) are far beyond what most people will ever drive at. If this one is only rated to 130km/h, that decreases the safety factor.
During passing it's easy to push above 80 mph (the quoted rated speed for these tires) and for many freeways 80-85 is just the flow of traffic. Either way I'd rather not operate near the failure point of anything while driving long distances.
People may push to 90 or 100 for very short, infrequent periods. Even a 2002 station wagon is perfectly capable of doing that - you wouldn't expect the tires to just fail at any speed the car is capable of attaining.
In Poland the legal motorway speed limit is 90mph(which means there is a lot of traffic moving at 100-110mph). In neighboring Germany you can drive much faster than that. An 80mph tyre would be useless.
It seems possible to me that 80 mph is a milestone that's been hit - not the final rating. Stability at 80 mph is probably better than they've done before, so they can push to the next milestone.
Great article about a previous innovation of Michelin that failed: In the 1990s Michelin developed a revolutionary new kind of tire with sensors and an internal hard wheel that could run almost perfectly for 125 miles after a puncture. They forgot to involve the ecosystem.
I am pretty happy with my run flat tires on my bmw, even after a blowout they remain normal and handling is near normal as well, plus you can drive like 100miles and 50mph to a nearest tire shop. The only downside is they are more expensive and sometimes if you cought nail close to a tire sidewall it means you I'll have to replace a tire since it's not fixable
And they ride more harshly, are less compliant, are heavier (look at how much some spend on light-weight rims; tires are even further from the center of the wheel), more expensive, can get bent / dented, and rely on finicky tire pressure monitoring systems.
I used to replace a lot of run flats on BMWs and they are all of that. Plus because the sidewall is so thick they're a huge pain in the ass to get on the rim so chances of rim damage is much higher when you put these on. Even with helper arms on the machine they're still difficult.
The thick side wall makes for a bad ride in my opinion. The difference is pretty significant.
Beyond the issue with unsprung weight, that seems like a truly awful trade-off. A run-flat still needs to be serviced if punctured and is still vulnerable to sidewall damage and potential blow-outs. If you carry a full size spare (I sure do) in the event of most tire failures, you still have the ability to get much further down the road with less drama.
None of the new sedan vehicles carry a full sized tire, they all carry a temporary one, which can only be driven 50 miles at low speed. So still worse than broken run flat
They don't come with one stock, sure, but there's nothing to stop you from going and buying the correct sized steel (or cheapo alloy) wheel and a decent tire that's the same size as the ones on the car and carrying it with you (and throwing the junky temporary spare out). Yeah it requires you to work a touch extra on the setup, but it is worth it. The extra full size spare will cost about the same as going with run flats vs non-run flats each time you swap out tires.
If you're interested, it's pretty easy to get the correct sized wheel from somewhere like RockAuto or Discount Tire Direct.
I have a 5 series bmw (f10 latest one), and I have had other premium cars before and I (and many car experts) can tell you nothing comes close in this price range in terms of handling and comfort of BMW, run flat tires make no difference for me compared to regular tires on my previous Merc and my friend's audi a6.
Why downvoting? It's my personal experience and opinion? Sometimes I don't understand HN users...
I didn't downvote you, but I'd guess the reason was that you brought an irrelevant fact to a discussion about run-flat vs regular tires - it doesn't really matter if a BMW with run-flat still has better handling than an Audi with regulars.
I was also under the assumption that if you actually drive the 50-100 miles on your run-flats after they've been punctured, then the tire will be so damaged as to require replacing.
I have run-flats on my Mini, and the Mini community very adamantly insists that regular tires are smoother, quieter and offer much better traction. I plan to make the switch soon.
The demo video touts them as "eco-friendly", and I'm assuming they mean relative to traditional pneumatic tires, so how are they actually better in that regard?
There might be multiple factors: how much you pollute to produce them (much less, considering that there is almost no metal involved, unlike with traditional tires which have alloy wheels); how much they get consumed by usage, compared to traditional tires; how much they pollute to dispose of them.
Normal tires are terrible to recycle. You have to grind them up, sift out all the metal pieces, and then you have some poor quality recycled rubber to use for something.
That's a cool video, but I've seen enough CG-salesy examples from vaporware projects--with similar animation and admittedly high-quality concept videos--to feel skeptical.
Given how well similar tires seem to work for the military, and potentially low-cost replacement road-contact parts, I'd support it. However, my worry is... what if the manufacturer and or distributor went out of business? Will I have to replace all my tires just because one got a little shredded up from some debris? (I assume mixing tires which might have different sizes / radiuses is a bad idea)
Watch for stats on rolling resistance, tire weight, impact on suspension / size, and cost before getting excited.
Punctures occasionally cause blowouts, and those are awful, but still subject to tradeoffs. If airless tires tank the efficiency of your vehicle you'll think to yourself, "Well, I've never had a catastrophic blowout... and changing a tire is a pain, but isn't that bad."
We've used airless for decades, just not in cars. We aren't just waiting for a simpler manufacturing process, there are other constraints at play.
No. The purpose of run-flat tires are to get you to pull off the road safely, or travel a small number of miles at low speeds to somewhere where you could have a replacement mounted and installed immediately. They are not intended to run without air for extended periods of time, or at highway speeds. They are also not to be driven on AT ALL in the event of a sidewall puncture.
The casing would still fail catastrophically at high speeds (i.e. pursuit scenario), and having a tire down over 30psi on one wheel would very seriously affect handling at any significant speed (40mph or more).
I'd be interested in better efficiency and lower operating cost. As for safety, I'd have to see the stats on how often modern tires blow out. And a demonstration that lower operating costs on the tires doesn't translate into higher costs for maintaining other components such as bearings and suspension.
I wonder if you can 3d print a rubber tire shape someday. You might be able to engineer a shape that might be hard to make otherwise and solve some of the issues not having air.
I'd be interested to know how well layers of 3d printing holds up to that much rotational mass, lateral forces, and vibration at freeway speeds. I have my doubts at this point of its feasibility.
NinjaFlex is a new type of material that some people are printing for rubber-like things, including little toy tires. Don't think it's ready for a car yet, but it's fun to play with.
Puncture proof bike tires work extremely well. I have Continental Top Contact tires. Except for overinflation (my fault), never had a flat over thousands of miles. They feel nice to ride on too. Before that, I had Panaracer ribmo tires. No flats, ever. However, the ride was a little bit stiff.
Both were a little heavy, but worth the extra weight.
If you're getting flats, that's a much better solution.
We were given some airless tires a few years ago by two different manufacturers to test on some bicycle trailers. Our experience was the tires performed find when the trailers were empty, but the rolling resistance was noticeably higher than a pneumatic tire when the trailer was loaded--so much more, in fact, that we discarded them immediately after the test.
I think the best solution is to use pneumatic tires with a Kevlar liner built into the tire casting.
Rent-a-bikes in my city actually use airless tires, so they seem to already exist for this purpose. I don't know what is inside, but from the outside they look like normal bike tires. The ride is noticeably less comfortable though.
These have been around a long tme, especially for armored cars (I saw them on an Audi W12). I was told the ride is rougher than pneumatic tires but have the advantage that they can't be punctured by gunfire, or whatever.
Personally, I want some Mattracks :) (https://www.mattracks.com/)