# Bullet proof tires! **URL:** \ **Category:** Factual Questions\ **Created:** [June 11, 2005, 1:34pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854 "2005-06-11T13:34:57Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Mac\_Guffin](https://avatars.discourse-cdn.com/v4/letter/m/2bfe46/32.png) [@Mac\_Guffin](https://boards.straightdope.com/u/Mac_Guffin)\ **Post date:** [June 12, 2005, 9:17am UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/21 "2005-06-12T09:17:24Z")
As far as foam filled tires go, when I was a General Purpose Vehicle Mechanic in the U.S.A.F, our security guys drove around in little armored cars called PeaceKeepers. It was just a Dodge truck frame with a thin armored body attached. The tires on them were originaly foam filled, as was mentioned earlier. They weighed over 300 lbs so were tough to change, (you needed a special jack just to get them on and off the hub) and tough to balance. It was a common prank to play on newbs to have them check the tire pressure on them. (no valve stem.) About mid way through my tour, the AF switched to a runflat type tire with a big rubber insert that weighed a hell of a lot less. We were very pleased with this. One other problem with these hogs was their amp gauges. The gauges in the dash were rated for up to 60 amps, but the vehicles shipped from the factory with 100 amp alternators. I ended up changing out many an instrument panel and wiring on those things after the gauge would burn out/up. ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [June 13, 2005, 3:00pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/22 "2005-06-13T15:00:10Z")
> [@Nanoda](#): > > Good call - Ok, the final product would surely have the side blocked off (perhaps transparent for kewlness) because like you said, mud or (definately around here) ice and snow would make for _seriously_ unbalanced wheels.[/SIZE] This would take some serious work, I’d think - You’d need a sidewall barrier that was road-hazard resistant, and every bit as flexible as the the structural webbing. ---
**Author:** ![Metacom](https://avatars.discourse-cdn.com/v4/letter/m/ecae2f/32.png) [@Metacom](https://boards.straightdope.com/u/Metacom)\ **Post date:** [June 13, 2005, 3:33pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/23 "2005-06-13T15:33:48Z")
> [@Tranquilis](#): > > This would take some serious work, I’d think - You’d need a sidewall barrier that was road-hazard resistant, and every bit as flexible as the the structural webbing. Hmm… Maybe rubber? Perhaps with steel belts embedded inside? 😉 ---
**Author:** ![Tranquilis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tranquilis/32/3639_2.png) [@Tranquilis](https://boards.straightdope.com/u/Tranquilis)\ **Post date:** [June 13, 2005, 3:57pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/24 "2005-06-13T15:57:14Z")
> [@Metacom](#): > > Hmm… Maybe rubber? Perhaps with steel belts embedded inside? 😉 Maybe you could inflate them to give a firm surface that would resist snagging…? ---
**Author:** ![GaryM](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/garym/32/241_2.png) [@GaryM](https://boards.straightdope.com/u/GaryM)\ **Post date:** [June 13, 2005, 6:40pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/25 "2005-06-13T18:40:38Z")
If you want foam filled tires, just go visit your nearest tractor dealer. Farm tractors are regularly run with foam filled tires. Two reasons: they can’t go flat, and they are heavier which makes the tractor more stable as well. Tractor tires are often filled with fluid which aids stablity, and aids traction, but does nothing for flat tire reduction. ---
**Author:** ![Jman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jman/32/4416_2.png) [@Jman](https://boards.straightdope.com/u/Jman)\ **Post date:** [June 13, 2005, 7:49pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/26 "2005-06-13T19:49:24Z")
> [@Drum God](#): > > While not bulletproof, or bullet resistant, they are virtually unbreakable in normal use. If the head breaks, it’s because some component other than the Kevlar failed – such as the crimping around the edge. You never played with my line mates. On my snare line in HS, we used Falams heads, and two of the other guys manged to play a hole through the head by the end of the season. True, they were beating the crap out of the head playing as hard as they could (when on their own, not during a show or parade or anything), but I have seen a kevlar head in tatters from stick wear alone. Since I wasn’t an idiot, my head usually just had discoloration on the sweet spot and some very mild surface wear. ---
**Author:** ![flight](https://avatars.discourse-cdn.com/v4/letter/f/bbce88/32.png) [@flight](https://boards.straightdope.com/u/flight)\ **Post date:** [June 13, 2005, 8:53pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/27 "2005-06-13T20:53:26Z")
> [@matt](#): > > Good post! > > Re the OP - kevlar is not automatically “bullet proof” or even bullet resistant. It needs to be woven and layered appropriately to capture a bullet and absorb its energy. Lesser fibres such as drawn nylon and silk can be woven into good soft armour as well. Carbon fibre is stronger than kevlar, but doesn’t have as good energy-absorbing properties (elasticity) and so hasn’t been used for this application as far as I know. Spider silk is very promising, but you can’t _get_ enough of it from spiders. Genetic modification of other organisms may create a source of spider silk. And it may find other uses unrelated to armour. Carbon has a nasty tendency to fail badly. It would turn a normal slug into a thousand flechettes. ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [June 14, 2005, 6:09am UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/28 "2005-06-14T06:09:56Z")
> [@Tranquilis](#): > > This would take some serious work, I’d think - You’d need a sidewall barrier that was road-hazard resistant, and every bit as flexible as the the structural webbing. You know, now that I think about it, you _could_ (possibly) get the tweel to work without sidewalls. It would all depend upon the pitch of the spirals as to what direction the crap was spewed out. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [June 14, 2005, 5:08pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/29 "2005-06-14T17:08:29Z")
Yeah, what I was just thinking, apex the inner surface a bit in the middle or on either side depending on where you want the most throw and it should self clean pretty good. A sliding skid could jam stuff up but still, for the way I use a 4 wheeler anymore, I like then as is. I am used to doing a ‘pre-flight’. Does anyone remember the old idea of a Rollermogon or some such? Had giant airbag sausage shaped rollers front and rear and could roll a heavy piece of equipment over a person without harm. that was another idea I liked for a lot of applications. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [June 15, 2005, 7:34am UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/30 "2005-06-15T07:34:13Z")
> [@flight](#): > > Carbon has a nasty tendency to fail badly. It would turn a normal slug into a thousand flechettes. Interesting. I presume you’re talking about carbon fibre in a composite material? Do carbon fibre composites tend to splinter? I have no experience with composites. I’m not so sure a woven carbon fibre fabric would fragment. And the fibres are very fine - can’t see them acting as flechettes. But maybe I’m completely misunderstanding you! ---
**Author:** ![jnglmassiv](https://avatars.discourse-cdn.com/v4/letter/j/f07891/32.png) [@jnglmassiv](https://boards.straightdope.com/u/jnglmassiv)\ **Post date:** [June 15, 2005, 8:37am UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/31 "2005-06-15T08:37:35Z")
What are the ballistic plate inserts for body armor made of and what sort of rounds can they stop? ---
**Author:** ![Tuckerfan](https://avatars.discourse-cdn.com/v4/letter/t/eada6e/32.png) [@Tuckerfan](https://boards.straightdope.com/u/Tuckerfan)\ **Post date:** [June 15, 2005, 8:49am UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/32 "2005-06-15T08:49:09Z")
> [@jnglmassiv](#): > > What are the ballistic plate inserts for body armor made of and what sort of rounds can they stop? IIRC, they’re called “knife plates” and are intended to stop a knife, since body armor will stop a bullet, but not a knife. ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [June 15, 2005, 1:28pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/33 "2005-06-15T13:28:11Z")
> [@jnglmassiv](#): > > What are the ballistic plate inserts for body armor made of and what sort of rounds can they stop? A lot of them are ceramic tile. [http://www.ceramicindustry.com/CDA/ArticleInformation/features/BNP\_\_Features\_\_Item/0,2710,100934,00.html](http://www.ceramicindustry.com/CDA/ArticleInformation/features/BNP __Features__ Item/0,2710,100934,00.html) Steel liner plates are avaible for soft armour for stopping knives, as **Tuckerfan** says. There is now soft armour that will stop knives without liners, but there wasn’t always. I’ve no idea how it works, even in theory. ---
**Author:** ![flight](https://avatars.discourse-cdn.com/v4/letter/f/bbce88/32.png) [@flight](https://boards.straightdope.com/u/flight)\ **Post date:** [June 17, 2005, 3:22pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/34 "2005-06-17T15:22:18Z")
> [@matt](#): > > Interesting. I presume you’re talking about carbon fibre in a composite material? Do carbon fibre composites tend to splinter? I have no experience with composites. > > I’m not so sure a woven carbon fibre fabric would fragment. And the fibres are very fine - can’t see them acting as flechettes. But maybe I’m completely misunderstanding you! Yeah, they splinter something nasty. When the woven fabrics fail they create many small sharp shards. They tned not to go down to the individual fibers as much as breaking into many small knives. I was designing a sail plane in a class and carbon was the material of choice for much of it, but we could not use it for the nose area, as in the event of a crash it would cuisinarte the pilot. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [June 17, 2005, 3:39pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/35 "2005-06-17T15:39:48Z")
> [@flight](#): > > I was designing a sail plane in a class and carbon was the material of choice for much of it, but we could not use it for the nose area, as in the event of a crash it would cuisinarte the pilot. Can’t you add a couple layers of Kevlar to the CFRP? That’s what streamlined HPV (human-powered vehicle) builders usually do, and they’re up to the 80mph range these days. ---
**Author:** ![flight](https://avatars.discourse-cdn.com/v4/letter/f/bbce88/32.png) [@flight](https://boards.straightdope.com/u/flight)\ **Post date:** [June 21, 2005, 12:28pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/36 "2005-06-21T12:28:56Z")
It’s possible, I imagine. Weight was a serious issue though and the amount of Kevlar needed to prevent the carbon fiber from killing someone was about equal to the amount of Kevlar you would need with no carbon fiber. ---
**Author:** ![sewalk](https://avatars.discourse-cdn.com/v4/letter/s/b3f665/32.png) [@sewalk](https://boards.straightdope.com/u/sewalk)\ **Post date:** [June 21, 2005, 1:12pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/37 "2005-06-21T13:12:06Z")
> [@jnglmassiv](#): > > What are the ballistic plate inserts for body armor made of and what sort of rounds can they stop? They are used to take body armor to Level III or IV. Level III is resistant to rounds up to 7.62mm NATO FMJ at 2750fps. Level IV can handle .30-06 AP(Cartridge, .30, M2) at 2850fps. I have seen them made of (in ascending thickness) titanium, steel, ceramic, and plastic. Level IV plates are obviously thicker than Level III. ---
**Author:** ![chrisk](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@chrisk](https://boards.straightdope.com/u/chrisk)\ **Post date:** [June 21, 2005, 1:17pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/38 "2005-06-21T13:17:54Z")
> [@Fargesto](#): > > Hi > > Program on TV the other day where chase police shot out the tires of suspect vehicle to make him stop. > > So why are tires not bullet proof? > > 🙂 [simplistic answer]So that the police can shoot out the tires of suspects to make them stop?? 😃 When you think about it, most law-abiding drivers don’t really need to worry about their tired getting shot out. Sure, criminals could try doing it as a form of robbery, but they wouldn’t be able to effectively carjack the vehicle afterwards. And it seems like a vaguely useful technique for the authorities to keep scofflaws from making their getaway. Just my $0.03 worth (after inflation.)[/SA] ---
**Author:** ![matt](https://avatars.discourse-cdn.com/v4/letter/m/a6a055/32.png) [@matt](https://boards.straightdope.com/u/matt)\ **Post date:** [June 21, 2005, 3:13pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/39 "2005-06-21T15:13:35Z")
> [@flight](#): > > When the woven fabrics fail they create many small sharp shards. Sorry to be a pain, but just to clarify. Are you talking about the fabric after it’s been laid down in layers and bonded with resin here? If you take the fabric while it still _is_ fabric, off the roll, hang it up and shoot it, how does it make sharp shards? ---
**Author:** ![flight](https://avatars.discourse-cdn.com/v4/letter/f/bbce88/32.png) [@flight](https://boards.straightdope.com/u/flight)\ **Post date:** [June 21, 2005, 8:45pm UTC](https://boards.straightdope.com/t/bullet-proof-tires/307854/40 "2005-06-21T20:45:34Z")
If you have ever worked with carbon fiber stringers (long lengths of fiber not woven) you know that they are like little pins that easily pierce the skin. If you were to take a woven carbon fabric and shoot it, you would punch holes through it that would shatter the individual strands and send many tiny fragents flying behind. If you had this as a vest it would be like being shot and filling the wound with fiberglass insulation, which if you have ever installed it you know gets into your skin and irritates like crazy. Once the fabric has been impregnated with resin and cured, though, things are different. A well made piece of carbon fiber is designed to never fatugue, but to fail catastrophically. When this happens it creates many jagged little knives of resin bound fiber, not individual strands like in the dry fabric. You can see this effect if you take a piece of cured carbon fabirc and bend it until it cracks. The edge is just nasty. The way carbon fails makes it dangerous certain applications as it does not fail gracefully. Kevlar does, and thus is more appropriate for applications where you are trying to protect things, even though it is not as strong. [Previous page](https://boards.straightdope.com/t/bullet-proof-tires/307854.md?page=1) [Next page](https://boards.straightdope.com/t/bullet-proof-tires/307854.md?page=3)