# Why haven't flat-proof tires been invented? **URL:** \ **Category:** Factual Questions\ **Created:** [December 3, 2011, 5:48pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961 "2011-12-03T17:48:53Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![FoundWaldo](https://avatars.discourse-cdn.com/v4/letter/f/dfb087/32.png) [@FoundWaldo](https://boards.straightdope.com/u/FoundWaldo)\ **Post date:** [December 3, 2011, 5:48pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/1 "2011-12-03T17:48:53Z")
It seems that with all the technology we have today, it would be possible to make a tire that is nearly impossible to go flat. I know about runflats, but those are more like a built-in emergency spare than a true “flat-proof” tire. Why can’t they put in a layer of airtight material that is puncture-proof, so a nail or screw can never get through to the air chamber? ---
**Author:** ![Lasciel](https://avatars.discourse-cdn.com/v4/letter/l/e79b87/32.png) [@Lasciel](https://boards.straightdope.com/u/Lasciel)\ **Post date:** [December 3, 2011, 5:52pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/2 "2011-12-03T17:52:43Z")
Or just leave the air out of the question entirely. [Airless Lunar Tires](http://www.scientificamerican.com/article.cfm?id=airless-tires-lunar-wheel) According to the article, both Michelin and the military have been working on various incarnations of airless tires. Apparently materials technology has to get to a certain level for the tire to function as well as consumers expect it to in comparison to traditional ones. ---
**Author:** ![Xema](https://avatars.discourse-cdn.com/v4/letter/x/9de053/32.png) [@Xema](https://boards.straightdope.com/u/Xema)\ **Post date:** [December 3, 2011, 6:12pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/3 "2011-12-03T18:12:28Z")
Several companies are working on the airless tire concept, including [Michelin](http://www.fastcoolcars.com/airless-tires.htm) and [Bridgestone](http://technabob.com/blog/2011/12/03/bridgestone-airless-tires/). ---
**Author:** ![Alka\_Seltzer](https://avatars.discourse-cdn.com/v4/letter/a/c89c15/32.png) [@Alka\_Seltzer](https://boards.straightdope.com/u/Alka_Seltzer)\ **Post date:** [December 3, 2011, 6:27pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/4 "2011-12-03T18:27:35Z")
The air in a tyre helps improve ride comfort, by allowing it to deform and absorb bumps in the road. The pressure can also be adjusted to keep as much as possible of the tyre in contact with the road, for the best cornering and braking performance (it’s the tyres that stop the car, not the brakes). Replacing traditional tyres with a solid material that provides a similar performance at similar cost is not a trivial task. ---
**Author:** ![voltaire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/voltaire/32/313_2.png) [@voltaire](https://boards.straightdope.com/u/voltaire)\ **Post date:** [December 3, 2011, 7:15pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/5 "2011-12-03T19:15:08Z")
There’s also the matter of weight. “Unsprung weight” has a significant impact on performance, and more importantly, fuel economy. ---
**Author:** ![Alessan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/alessan/32/465_2.png) [@Alessan](https://boards.straightdope.com/u/Alessan)\ **Post date:** [December 3, 2011, 7:29pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/6 "2011-12-03T19:29:51Z")
Because unobtainium can only be found on Pandora, and we all know how \*that \*turned out. ---
**Author:** ![KneadToKnow](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kneadtoknow/32/3999_2.png) [@KneadToKnow](https://boards.straightdope.com/u/KneadToKnow)\ **Post date:** [December 3, 2011, 7:30pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/7 "2011-12-03T19:30:02Z")
> [@FoundWaldo](#): > > Why can’t they put in a layer of airtight material that is puncture-proof, so a nail or screw can never get through to the air chamber? To address a different part of this question, some flats are not caused by punctures. Some are caused by out-of-round wheels which create slow leaks, which if unnoticed in turn cause the sidewalls of the tire to deform, sometimes beyond the design limits of the tire, resulting in sidewall blowouts. Ask me how I know. ---
**Author:** ![RickJay](https://avatars.discourse-cdn.com/v4/letter/r/bb73d2/32.png) [@RickJay](https://boards.straightdope.com/u/RickJay)\ **Post date:** [December 3, 2011, 7:32pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/8 "2011-12-03T19:32:19Z")
Well, heck, I have an airless tire in my trunk; the spare emergency tire. So they do exist. It’s just that they suck in a thousand other ways. The challenge isn’t just to create an airless tire, but to create an airless tire that’s as cheap as the cost of a regular tire plus the likelihood of the inconvenience, risk and cost of a flat tire. I’ve been driving for 24 years and have gotten two flat tires that I can recall. Unless your airless tire is very nearly as cheap as the ones I have now, you can’t convince me to switch; I’ll pay a little more, **assuming they are every bit as good in every other way** , but not that much more. The likelihood of my getting a flat is, based on my experience, pretty tiny, and it’s really not an enormous hassle to get it fixed. ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [December 3, 2011, 7:41pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/9 "2011-12-03T19:41:38Z")
I’ve read an article on the airless tires being developed by Michigan and others (they look similar to a bike’s tire, and have a sort of semi-rigid spoke system that has some give to try and make the ride as comfortable as a traditional tire), the problem with all of them is I think the best ones they make right now can only provide a comfortable ride up to about 35 mph, and are serviceable up to about 50 mph and anything faster than that you really can’t go on those tires. As **RickJay** says, such a tire would have to provide a comfortable ride up to at least full interstate speeds _and_ not cost 2-3x as much as a regular tire and be just as good in all other ways for them to catch on. The only way I could see them being popular is if they equaled a regular tire in every way, cost dramatically more, but had a longer life, such as the life of the car or something. The only way most people will justify paying 4x as much for a tire is if it’s going to last 4x as long. ---
**Author:** ![FoundWaldo](https://avatars.discourse-cdn.com/v4/letter/f/dfb087/32.png) [@FoundWaldo](https://boards.straightdope.com/u/FoundWaldo)\ **Post date:** [December 3, 2011, 7:47pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/10 "2011-12-03T19:47:16Z")
The problems of airless tires is why I thought it would be better to have inflated tires with a puncture-proof layer. Yes, flats are relatively uncommon, but when they happen in the middle of a rainy night on a freeway with a narrow shoulder, they really, really suck. Obviously there are ways to get flats other than punctures, but all of the (few) flats I’ve had in my life time have been the result of something sharp and metal puncturing the tire. I personally would be willing to pay a significant premium for a tire that made those flats nearly impossible, assuming the tire’s performance was otherwise the same as a regular tire. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [December 3, 2011, 8:05pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/11 "2011-12-03T20:05:15Z")
> [@FoundWaldo](#): > > The problems of airless tires is why I thought it would be better to have inflated tires with a puncture-proof layer. Yes, flats are relatively uncommon, but when they happen in the middle of a rainy night on a freeway with a narrow shoulder, they really, really suck. Obviously there are ways to get flats other than punctures, but all of the (few) flats I’ve had in my life time have been the result of something sharp and metal puncturing the tire. I personally would be willing to pay a significant premium for a tire that made those flats nearly impossible, assuming the tire’s performance was otherwise the same as a regular tire. the problem is that the tire’s structure comes in part from the steel belts and cloth/aramid reinforcements in the sidewall. They’re cloth/woven because they need to be flexible, and anytime you have something woven or braided, a sharp object can poke its way through. in the past there were [Uniroyal Royal Seal tires,](http://books.google.com/books?id=PAEAAAAAMBAJ&pg=PA14&lpg=PA14&dq=royal+seal+tires&source=bl&ots=AGvcyW5K-1&sig=8PjKcmIJ5mnGoe59ECvR260r_xc&hl=en&ei=6X_aTsTCFeiK2wWw6_3bDg&sa=X&oi=book_result&ct=result&resnum=9&ved=0CLYBEOgBMAg4Cg#v=onepage&q=royal%20seal%20tires&f=false) which had a layer of soft rubber on the inside surface of the tire; it was almost like the consistency of that rubbery stuff they use to fill cracks in pavement. Problem was it made the tire heavy, and if the tire got too warm, the sealant would flow and [throw the tire out of balance.](http://autopedia.com/APBB/Forum1/HTML/001101.html) Back in the day I had a couple customers ask me to try to balance a royal seal tire, and after not being able to get it in balance I took the tire off of the rim and found a big lump of the sealant collected on one side of the tire. Unfixable, sorry. ---
**Author:** ![Great\_Antibob](https://avatars.discourse-cdn.com/v4/letter/g/e47c2d/32.png) [@Great\_Antibob](https://boards.straightdope.com/u/Great_Antibob)\ **Post date:** [December 3, 2011, 8:51pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/12 "2011-12-03T20:51:20Z")
> [@RickJay](#): > > Well, heck, I have an airless tire in my trunk; the spare emergency tire. Which model is that? I only ask because none of my spares have ever been airless. You occasionally get full sized spares, but most of mine have been the compact spares that are pressurized differently than the normal tires. AFAIK, you are typically recommended to check the pressure in your spare on a regular basis, as well. ---
**Author:** ![SandyHook](https://avatars.discourse-cdn.com/v4/letter/s/dec6dc/32.png) [@SandyHook](https://boards.straightdope.com/u/SandyHook)\ **Post date:** [December 4, 2011, 1:11am UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/13 "2011-12-04T01:11:15Z")
I was looking at this thread earlier today and had nothing to add. A few minutes ago I ran into [this.](http://www.stumbleupon.com/su/1F5FKv/www.physorg.com/news/2011-12-bridgestone-airless-concept-tokyo.html) ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [December 4, 2011, 3:29am UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/14 "2011-12-04T03:29:02Z")
Barely a week after getting my new car, the value, but especially the _convenience_, of its [“Run Flat” tires](http://en.wikipedia.org/wiki/Run-flat_tire)was made more than clear to me. ---
**Author:** ![Daylate](https://avatars.discourse-cdn.com/v4/letter/d/9dc877/32.png) [@Daylate](https://boards.straightdope.com/u/Daylate)\ **Post date:** [December 4, 2011, 5:40pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/15 "2011-12-04T17:40:46Z")
Heck, back in the good old days (1920 or so), IIRC most if not all truck tires were “run flat”, being made out of solid rubber. Worked like a charm, but there were a few downsides. ---
**Author:** ![Martin\_Hyde](https://avatars.discourse-cdn.com/v4/letter/m/47e85d/32.png) [@Martin\_Hyde](https://boards.straightdope.com/u/Martin_Hyde)\ **Post date:** [December 4, 2011, 5:46pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/16 "2011-12-04T17:46:16Z")
> [@KarlGauss](#): > > Barely a week after getting my new car, the value, but especially the _convenience_, of its [“Run Flat” tires](http://en.wikipedia.org/wiki/Run-flat_tire)was made more than clear to me. Run flat tires have their problems, too. I had them on a car a few years ago and because of their inherent rigidity when one of them actually ran over something that punctured the tire I ended up with both a tire needing to be replaced and bent rims. So instead of just having to replace a tire I had to replace an expensive tire (as run flats are premium in price) and the rim. ---
**Author:** ![naita](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/naita/32/5862_2.png) [@naita](https://boards.straightdope.com/u/naita)\ **Post date:** [December 4, 2011, 6:20pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/17 "2011-12-04T18:20:51Z")
> [@FoundWaldo](#): > > It seems that with all the technology we have today, it would be possible to make a tire that is nearly impossible to go flat. I know about runflats, but those are more like a built-in emergency spare than a true “flat-proof” tire. Why can’t they put in a layer of airtight material that is puncture-proof, so a nail or screw can never get through to the air chamber? Because all known airtight, puncture-proof materials make the tire horrible at tireing. ---
**Author:** ![ctaylor](https://avatars.discourse-cdn.com/v4/letter/c/6f9a4e/32.png) [@ctaylor](https://boards.straightdope.com/u/ctaylor)\ **Post date:** [December 5, 2011, 9:51pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/18 "2011-12-05T21:51:28Z")
The reproduction 1870s penny farthing (high wheel) bicycle I have has solid rubber tires. That’s one bike I’ll never get a flat on! It didn’t take long for some inventors, among them some gentlemen by the name of Dunlop and Michelin to bring out pneumatic tires that were quickly adopted because they made bicycles a lot more fun to ride. That was around the 1890s. ---
**Author:** ![Sarabellum](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sarabellum/32/3492_2.png) [@Sarabellum](https://boards.straightdope.com/u/Sarabellum)\ **Post date:** [December 5, 2011, 10:40pm UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/19 "2011-12-05T22:40:29Z")
This thread has become rather flat and tiresome. ---
**Author:** ![tellyworth](https://avatars.discourse-cdn.com/v4/letter/t/977dab/32.png) [@tellyworth](https://boards.straightdope.com/u/tellyworth)\ **Post date:** [December 6, 2011, 12:34am UTC](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961/20 "2011-12-06T00:34:12Z")
> [@FoundWaldo](#): > > Why can’t they put in a layer of airtight material that is puncture-proof, so a nail or screw can never get through to the air chamber? Some bicycle tyres do. They make them somewhat more resistant to punctures, but by no means immune - as others have said there are various different ways for a tyre to go flat. They also have other tradeoffs, like extra weight, more rolling resistance, perhaps a less comfortable ride. There have been any number of anti-puncture tyres and things made for bicycles. Most of them turned out to be far worse than the inconvenience of an occasional flat. A few have been incorporated as incremental improvements to normal tyres. [Next page](https://boards.straightdope.com/t/why-havent-flat-proof-tires-been-invented/604961.md?page=2)