I completely disagree with the big rig tire explosion experiment. There are too many variables. Was the tire a virgin carcass or a re-capped tire? How many miles were on the tire carcass? And the explanation for tire flex was very vague. The tire flexes from the weight of the vehichle on it. Plus the trailer was empty. A proper test would be with a recapped tire, inflated to 100 PSI, 80,000 pounds of freight in the trailer, run the tire around 75 mph, and leave full weight of the trailer on the tires just like it would be running on the road. These would be real world conditions. I am a diesel mechanic and have seen tires blow out.
I completely agree. I don't really know that much about trucks, but when I saw the episode I remember thinking that they didn't take into consideration enough variables. Another variable to think about...What about road conditions? Weather, wear of the road, etc...would that change anything?
My thoughts exactly. My experience was with a cap that came off while the truck was heavy and under way. There was no explosion, it simply threw a cap at me.
i would agree with you. just shortly after the episode i was watching shock video on the court channel and the show featured a highway patrol man whom nearly lost his head due to a tractor trailer blowout. the concusion knocked with the sound knocked the officer over and shrapnle flew past his head.
I would like to see this taken a different direction, one that might be easier to check.
Back when I was a truck mechanic, they used wheels with a "split rim". This was like a "C" ring on the outside of the wheel to hold the tire on. When the ring was set, they really held well. But if the ring didn't get set quite right, it could shoot off (so I was told) once under sufficient pressure. We used to inflate tires on these split rim wheels with the fork lift forks sitting down on top of the wheel just in case the ring decided to come off.
Maybe this myth had something to do with split rim wheels? If the ring wasn't set and the tire pressure went way up during driving, the ring would probably shoot off at 90 degrees to the direction of travel and there is a good chance the process would make a sound (and throw off bits) that could be taken as an explosion.
i saw this one and thought it would be interesting. The problem with the test was they got the myth wrong. They were saying the tire does the damage, it doesnt. It is the rim that does the damage. Trucks used to use a rim that came in pieces. It was held together with a huge split ring, that locked the whole rim together. When the tires would blow the split ring would sometimes fly off the rest of the rim and that would do the damage. Believe me they did come off with enough power to slice you up pretty good. NOt sure about cutting you in half but they could definatly kill you. I am in the Military and we have lost a number of people to this very thing over my career. I had one come apart on me in a safety cage and was lucky to be un hurt, you couldn't say the same for the cage,. it was destroyed. This is the main reason the industry got away from using the split ring tyoe of rim and went to the tubless rim. these are much safer. I owuld like the guys to test out the older style split rims that trucks used to use.
When I heard the "Myth" it was a split rim wheel on a big rig. Reportedly back in the 70s I heard report of a semi taking out a motorcyclist along highway 80. I did find the following websites about split rims. http://www.cdc.gov/niosh/face/stateface/mn/92mn008.html http://www.hss.state.ak.us/DPH/ipems/occupation_injury/reports/docs/03AK006.pdf http://www.osha.gov/dts/maritime/sltc/longshoring/section1/summary14.html
Hi. I am a log truck driver in northern CA. And I have had a few blowouts in my career. The most memorable ones are 1. I had a steer tire blowout at 65 mph. And it was a split rim wheel. The force of the blowout shot the split ring across thye highway, and intothe brush on the opposing traffic side. 2. I had a drive tire blowout at about 65mph. QAnd it threw thr tread completely off in one piece, and if flew straight up in the air, and came down directly on the hood of a car that was passing me. Needless to say the owner of the brand new shiny red car wasn't pleased.
Interesting about the different rim types. Also good point about being loaded.
I had a good blowout in a f-350 and the tire went flying from that. I can't imagine how much worse it would be when you scale it up to a semi.
I just thought it was funny when they were talking about using a dyno to power the wheel on their rig. A dyno doesn't power the vehicle that is on it. The vehicle runs and the Dyno just measures the HP and torque output by the vehicle.
This message has been edited. Last edited by: ak5000,
I am so glad that I am not the only person to realize this problem. A tire that is suspended will not explode the way they wanted it to. Whoever said they needed to put the tire on the ground with full freight is right. I've seen so many big rig tires explode on Interstate 80 in my life. I hope they can conduct the experiment again, and realize that it is possible. I'm not sure that this is even a myth.
It is now against the law for a retail outlet mount a tire on a split rim. Actually is has been for quite a while now. BTW they were nicknamed suicide rims back in the day and for good reason.
Another problem I see with the experiment is the relative speed of the two vehicles. Even accounting for a slow down of the debris after the explosion, there is no way it will have a 40MPH closing rate if both vehicles are going at highway speeds. I have been in the next lane when a truck tire blew. It did hit my windshield and put a crack in it. Considering this was a 70MPH zone this would have had more potential for injury that their 40mph test.
A few years ago I was on the highway about to pass a rig and was about 15-20 ft away when its outter leftmost tire blew. It was the equivalent to a small bomb. I could easily feel the concussion and heat from the blast inside my car and my windows were CLOSED. I have no doubt that if a motorcycle was next to that explosion that at the very least they would be knocked off and likely hit by any traffic that was behind them. And if any debris from the tire him them as well ... I don't think it likely they would walk away from that without a trip to the hospital.
I was a mechanic in the army and alot of military trucks still use split rims. When we changed the we had to put them in a big tubular steel cage to prevent them blowing apart. If they seperate the rim can fly and hurt people. I doubt it could decapitate someone, but it could easily smash a window and do serious damage or topple a motorcycle. The mythbusters looked at the wrong angle. Its not the tire, but the rim
i dont doubt that the shrapnel from a truck tire blowout could cause serious bodily harm, but i do have a bone to pick with how the mythbusters launched that piece of tire towards the ballistic gel head. thay said that they launched it after spinning the tire of the pickup up to 40mph.... it was actually more like 80mph. the opposite wheel on the drive axle of the pickup was held stationary. because of that, the differential action in the rear axle causes the free wheel of the drive axle to spin twice as fast as it would be if both wheels were spinning at the same speed. so when the speedometer on the pickup reads 40mph, the speed of the free spinning wheel is actually 80mph. this is because the speedometer uses the output speed of the transmission, not the actual speed of the wheel.
by the way, i am an ASE certified mechanic, so if you do research on anything i have said, you will find i know what im talking about.
I disagree on tire decapitating the driver. There are too many varibles For starters the window the tread was shot through was not a windshield so it was not as strong. From my expirence around trucks if you blow a tire its going to be shot up into the duals and back to the road not projected out and even if it was shot up it wouldn't go that high and if the truck was up to code the mud flaps would slow the tread on impact. If a tire is about to go it doesn't just shoot straight off anyway any operator who has any idea what hes doing can tell when a blow out is in process and can take action promptlt and in time slowing the truck and pulling off to the side. Therfore this can't evenbe plausible.
As mentioned earlier, the rim used makes a big difference. Split rims have been outlawed for many years and having been around them I can see why. The rim used in the episode was a more modern single piece, tubeless style rim. However, there is a legal interim, 2 piece style rim that, though deemed safe, can have catastrophic failures to the side of the tire, or along the axis of the axle where the retaining ring departs the main rim under certain conditions. Usually this is the result of poor maintenance where the ring or rim is damaged or is fouled with rust or debris.
I’m a driver and I’ve put more than a few thousands miles on in a Big Rig. I’ve driven brand new equipment and busted old pieces that shouldn’t have been on the road at all. I’ve ran “caps” and “virgins”. I’ve ran in all kinds of weather over all kinds of roads – paved and unpaved. And I’ve yet to have a catastrophic tire failure that did any damage to my own vehicle let alone someone else’s, and I’ve certainly never decapitated anyone with any part from my rig.
That being said, the way they went about testing the myth is inaccurate. They were on the right track with lowering the tire pressure because almost all tire failures are caused by low tire pressure, rather than over-inflation. However, as previously surmised, there are too many variables that can cause problems – road conditions, weather conditions, tire conditions, the weight of the load, and much more.
First of all, all Big Rigs run “dualies” ... meaning there are two tires on each end of the axle. The only exception to the “dualie” rule is something called a “super single” ... one tire that is almost as wide as a set of dualies on one rim at each end of the axle. Regardless of whether the truck is running “dualies” or “super singles”, almost all Big Rigs run tandems... meaning two axles at each point except for the steering axle. The only except to that rule is light-weight freight operations such who run single-axle trucks and trailers because they never, ever get close to running 80,000 pounds per truckload. Any truck that is going to be anywhere close to hauling 53,000 pounds of freight plus a 27,000 pound tractor-trailer combination is going to run tandem axles with “dualies” or “super singles” ... that is a real world set-up.
The trailer they used for their experiment only had one regular width tire and no tandems. This set-up should have improved their chances for creating a catastrophic tire failure; however, they didn’t factor in the weight of the load. I can’t speak for all Big Rigs on the road, but I haul grain; grain-haulers constantly and consistently run right at the 80,000 pound weight-limit for Big Rigs (53,000 pounds of grain plus another 27,000 pounds tied up in the tractor-trailer combination). The trailer they used was an empty 27-foot pup trailer that at most weighed in at 5,000 pounds. Then they removed almost all of the weight of that small trailer by holding it up with a large fork-life.
Attempting this experiment with an empty trailer didn’t apply enough force to “flex” the under-inflated tire as they tried to show. Without a live load pressing down on the tire, any tire failure in the real world is going to happen exactly as they showed – the tire will deflate with a hiss, and eventually the tread will separate from the sidewalls. However, without the force from a load, the chances are the tread will wrap itself around the axle rather than shooting out.
Regardless of the rig and the tire set-up – dualies, super singles and/or tandem or single axles – if the tire were to fail, the tread would not fire away from the truck in a straight-line as they showed because of the force of the air pressure within the tire will push the tread out in a circular pattern from the spinning tire. While it is plausible that a tire tread could decapitate someone, their test didn’t prove anything other than they can build something to shoot a tire tread in a straight line at an immobile object.
As for some of the arguments about “split rims”, they are illegal. “Split rims” (also known as widow makers) are no longer manufactured for use in the United States. Any reputable tire dealer is not going to place a tire on a “split rim”, instead they are going to either sell the driver a solid rim or tell them to go some place else for their tire work. “Split rims” haven’t been actively used in this country for at least 20 years, and probably more like 30 or 40 years. So that suggestion falls flat before it ever leaves the chute.
In my opinion as owner-operator with a safe driving record ... this myth is plausible but unproven. It is also my opinion that as a responsible driver, I am responsible for religiously checking my tire pressures daily – some times several times a day depending on the type of road I’m driving down. The tires hold up my load, and I don’t get paid if the load is upside down in the ditch – and I don’t maintain my safe driving record if I lose a truck or a load in the ditch.
This message has been edited. Last edited by: kim g,
I've had a truck tire explode next to me. We we're in Germany. My husband and I were going to the Base. A loaded German smi blew an outside tire. It was right next to me as close as they had Buster. The tire pieces that hit the car were no larger than 4 in. The largest tumbled away along the ground. We both were doing about sixty Miles an hour. We drove a 88 grand am then.
So I'd have to disagree with the tire going thru the window. All the bit of rubber I've seen on the side of roads are never flat. All are curled. And with that it would tumble and roll.
