Authorities suspect a steer-tire blowout was the root cause of a spectacular and deadly collision in New Mexico on August 30, just ahead of the Labor Day weekend. The crash took place on Interstate 40 near the town of Thoreau, close to the Arizona state line.
A truck heading eastbound on I-40 allegedly suffered a blowout of the right-hand steer tire, which appears to have caused the truck to veer across the highway, down through the median and directly into the path of a westbound Greyhound bus carrying 49 passengers. Seven people were killed in the crash, including the bus driver. The truck driver survived and was hospitalized with non-life-threatening injuries.
The incident received nationwide coverage from many media outlets and it's reported that the National Transportation Safety Board will investigate the crash. That means there will soon be a great deal of discussion about tire maintenance and probably driver training too.
We know that tires seldom, if ever, blowout arbitrarily. We also know that something like 80% of all tire blowouts are caused by deterioration of the tread and/or casing related to the heat caused by sidewall flexing of the underinflated tire. Most of the remaining 20% are road-hazard related. In this case, news camera images of the failed tire show tell-tale signs of an inflation-related failure.
As for the driver's reaction to the sudden loss of air pressure in his left-hand steer tire, the apparent path of the truck following the blowout strongly suggests he handled the incident improperly.
I want to stress here, I know nothing more about this crash than what has been reported in the media, and so whatever conclusions I can draw from what I have read and seen are pure but fairly well-informed speculation. I certainly do not know what happened at the moment the tire blew, but the reactions of a truck under such circumstances have been well-researched and documented, and this incident seems to bear witness to what can happen if the driver does not react properly.
What to do When a Tire Blows
A blowout on a steer tire will cause the truck to drop to the side of the blown tire and to begin pulling in that direction. An untrained driver's natural instinct once that pull is felt at the steering wheel would probably be to pull the wheel back in the opposite direction and to apply the brakes. Depending on the driver's reaction to the event, the steering-wheel pull and the brake application could be severe. Those two actions are exactly the wrong things to do.
The correct approach is to apply full acceleration and adjust the steering wheel to maintain a straight-forward course keeping the truck in the lane. Applying full power will accomplish most of that work, with a gentle correction of the steering required only to maintain directional control. The video below demonstrates this pretty clearly.
While it may seem counter-intuitive, it makes sense once you break it down. You have one steer tire, and a floppy one at that, pulling in the direction of the blowout, but you have four drive wheels pushing the truck in a straight line, presumably forward. By applying power, you increase the forward thrust from the drive wheels, which helps overcome the sideways pull of the blown tire. The steering correction necessary is minor.
That's all easy to say, here in the comfort of my office chair. What about the driver suddenly jolted to his or her senses by a loud bang and sudden change in direction?
It's to this point that I have often made comparisons between truck drivers and pilots. Pilots have it much easier as they have the benefit of altitude most of the time to make a correction and figure out what just happened. It takes a long time to fall from 40,000 feet. The poor truck driver has a fraction of a second to make a decision and only about 12 feet (two feet on either side of the truck) to play with.
Obviously, these situations call for fast reaction time, but the correct reaction too.
I have experienced two steer tire blowouts in my career. The first was a piece of metal that had fallen from a truck ahead of me. It was a trailer landing gear pad that was flipping and bouncing along the road. I wasn't able to steer around it, and it caught the left steer tire, cutting a big gash in the tread face. I was expecting this and reacted properly applying throttle and maintaining straight-ahead steering. Once the truck was stable, I slowed it down and pulled onto the shoulder ... and then waited three hours for a service truck.
The second was, I'm slightly ashamed to admit, a pressure loss failure. The right tire blew, shredding the tread and the casing. It took me a bit longer to react and I did lose lane position because I took my foot off the accelerator pedal. I drifted onto the shoulder, fortunately not into another vehicle. After a moment of drifting right, I got back onto the throttle and pulled the wheel left to get centered in the lane once again before slowing and pulling over.
Few drivers ever get the chance to practice such a maneuver in a less than game-on situation, but it's worth reading about, and watching these two videos. One is ancient, but still relevant, and the other covers blowouts on all three wheel positions; steer, drive and trailer. The corrective action for each is the same.
There are a few videos on YouTube that illustrate what can happen when a steer tire blows out. They all follow a pattern: the tire blows, the truck drifts in the direction of the blowout, the driver applies the brakes and loses control of the truck, or (alternate ending) the driver applies throttle and recovers control. Search "truck tire blowout" and see for yourself.
Such an event can really rattle your cage, but it's completely manageable if you do it right. Think about it from time to time while you're driving to keep the process straight in your head.
1) Apply full throttle
2) Correct for the steering drift
3) Once the truck is stable, decelerate slowly and pull over when it's safe to do so.
*CORRECTION: The story originally stated that the blown out tire was in the right-hand steer position. The blown out tire was in fact in the left-hand steer position.
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