Truck Tire Blowout Factors
While none of us experienced a truck tire blowout in trucking school, every one of us who drove big rigs commercially after graduation got to find out what it was like. You’ve noticed that trucks seem to have quite a few blowouts? It’s true. There are four factors that contribute to tire failure in the commercial sector:
1. High mileage that constitutes massive exposure. Most any full time over the road gearjammer will pilot his or her cargo hauling beastie a good 110,000 miles per year at minimum with some exceeding that figure by a fair margin. One friend of ours runs more than 150,000 miles per annum, year after year after year. That’s a lot of pure opportunity for a truck tire blowout.
2. Tire recaps. Most truck tires are not new, but rather tires that have worn the original tread down to a point and then been recapped. Recaps are not bad things: they simply are what they are…and what they are is a touch more vulnerable to blowout than something brand new from the factory. Steer tires are never recapped because a steer tire blowout can make you dead, but aside from that, a tractor-trailer combo is a rolling Recap City.
3. Careless maintenance. Many if not most truck tires are designed to operate at an inflation pressure of 110 psi. No one wants to run an underinflated truck tire. A driver will usually pretrip his truck by doing a walkaround and, among other things, rapping on each tire with a metal bar or even–my preferred tool for the task–a claw hammer. A skilled trucker can thus easily tell if a given tire has had a massive loss of pressure. But a more moderate loss, down to 100 psi or even 90 psi, will often go undetected until either the next trip to the company shop…or a blowout.
4. Heavy loads. Your personal car with two big guys (200 pounders) in it will have to carry a burden of something on the order of 900 pounds per tire or less. Each tire on an eighteen wheeler loaded to the maximum legal limit of 80,000 pounds is holding up 4,444 pounds. Yes, the truck tire is huge and tough in comparison to the tire on your favorite Chevy…but that’s still a lot of weight.
5. Mismatched tires. This generally happens after one tire from a set suffers a blowout. If a matching tire is not available, any tire of the right size and strength is an acceptable substitute. However, even if the replacement tire is exactly the same make and model as the others on that axle, it cannot possibly have exactly the same amount of wear–and thus is automatically a mismatch.
Some Truck Tire Blowouts I Have Known
During my admittedly limited stint of eighteen months as an over the road trucker fresh out of truck driving school, the truck-trailer combo I was driving had a number of blowouts. A few of the more “interesting” incidents were:
1. Sunday morning on the New Jersey turnpike. The trailer was loaded to the gills with heavy steel pipes. Destination: California. OTR (over the road) drivers love coast to coast runs like that because less time is lost loading and unloading and just plain waiting around to do either one. You only get paid for the miles you cover; excess wait time is depressing.
The blowout is like no other sound in the world. It’s not exactly “just like” a gunshot, but it gets a driver’s attention just about as well. As soon as possible, I pulled over to the shoulder to see what could be seen. The shattered tire was the outside rear trailer tire. Getting to a shop proved to be an exercise in ingenuity covering multiple states plus the Washington, D.C. beltway. With such a heavy load, It turned out that I could only run at 37 mph without overheating the “gone” tire’s partner. It was also illegal to drive a couple of hundred miles like that, so I did it anyway, skating through a chicken coop (weigh scale) safely…only because the missing tire was on the side away from the people in the scale booth.
After successfully reaching a truck stop in Virginia and calling our company dispatcher to authorize the cost, I was able to relax and enjoy a meal while a new tire (a recap, no doubt) was mounted and balanced…and away-y-y we go. Total lost time: About six hours. Could have been worse. Much worse.
2. Around nine-thirty p.m. in southern California, eastbound. This was another trailer tire, another heavy load, and another heavy traffic situation–though not as heavy as the New Jersey incident. A four-wheeler pulled off behind me, for what specific reason I don’t recall, and allowed me to use his cell phone to call dispatch. (I did not at that time own a cell phone.) It turned out that our company had a tire service outfit on call in that area. The dude showed up and replaced my rig’s missing rubber in record time. Total time at roadside: Under two hours. Awesome.
3. Early afternoon in southern Wyoming, northbound. This happened on a holiday, which proved to be unfortunate and then some. Finally pulling into a very small truck stop a whole bunch of miles from anywhere, I did manage to reach dispatch by phone…but the tire service company they supposedly called on my behalf never did show up. After numerous phone calls and zero satisfaction, it became obvious the cavalry wasn’t coming.
I had to make a decision. My delivery deadline was 6:00 a.m. the following morning at the Wal-Mart in Bozeman, Montana. Wal-Mart loads are light, so I could probably make it…if I didn’t blow another tire, and if I drove through the night. On the flip side of that coin, this blowout was on the tractor, not the trailer, and on the driver’s side to boot. If a Highway Patrolman noticed a truck running with a shiny steel wheel hanging out there with no rubber whatsoever, I could expect trouble.
So of course I did it. You’ve got that figured out about me by now, right? Not quickly, running all the way from central Wyoming to western Montana at 45 mph, but quickly enough to be there on time to unload. Then another couple of hours up the highway to my home terminal at Helena, Montana. Yup. Made it. Brought the shop foreman up to date and went on my days off for that month.
Summary: If you’re going to truck driving school to learn to drive the big rigs, you’re not likely to blow out a tire in school. But after graduation is when the real school begins, and over time you will leave some rubber on the road.