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| Featured Story
from the March /April 2008 Today's Tire Industry |
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TIRE REPAIR FOR TRUCKERS
by Glenn Kinyon
Contributing Editor
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My whole life is one long Seinfeld episode. Time and again someone will misunderstand what I say or misinterpret in a negative way something they saw me doing – or think they saw me doing – and often, when I discover what has happened, the explanation of the truth is so confusing or so difficult to put to words that I’m reduced to relegating the incident to fate and letting it go. But there are times when failing to resolve such a misunderstanding is too expensive to consider.
The supervisor at a trucking company that I service once told me with no little annoyance that they had to remove a tire that I had repaired from service. The driver was angry that I “plugged” his tire and he refused to drive on it. I informed the supervisor that I do not plug tires – I repair them properly. He would expose the lie, however. He rolled the tire in question, still mounted, out of his shop and directed my attention to the plug in the middle of a chalk circle. I tried to explain that what we were looking at was not a “plug” but a rubber stem – part of a proper repair. My words, however, did not seem to sink in with him.
 Then an idea struck me. I opened a fresh box of repair units and removed the instructions that came inside it. I unfolded the paper and handed it to him. He looked it over and then asked me how long they’ve been doing it that way. I told him it’s been that way for years. He said they still wanted their tires patched, and walked away. I then glanced down at the instructions in my hand and, to my frustration, realized that the side of the paper he looked at showed only the installation of the stem. The other side – the side he didn’t see – showed how to install the repair unit after the stem had been installed. He walked away still unaware that I had installed a repair unit in his tire.
And so it goes for me when someone watches me repair a tire for the first time. I can always tell what an observer is thinking. They’ve never seen anyone drill out an injury before and they wonder what the heck I’m doing to their good tire. They see the stem come through the hole and they cringe. I am, of course, in the onlooker’s eyes, plugging their expensive tire and I’ve just made the hole bigger to do it. For that reason, I try to make the repair unit obvious. I’ll hold it in my free hand and wave it around while I work or I’ll clench it between my teeth or balance it on my head until I’m ready for it. No matter – they won’t make the connection; I’m still plugging their tire. And stopping to give a watcher a lesson in proper tire repair is just awkward – it’s as if you’re trying to cover for your professional impropriety or something: “Yeah sure, buddy, if you say that’s how to fix a tire, who am I to argue?”
 If every tech repaired tires like they’re supposed to, this wouldn’t be an issue; but they don’t, and it is. Sometimes I wish I had a copy of an article to leave lying around to catch a customer’s eye. If I had such an article, I would want it to go something like this:
Attention truck drivers, fleet owners and supervisors – there is one correct method of tire repair. It involves the incorporation of both a repair unit, commonly referred to as a patch, and a rubber stem, commonly referred to as a plug, and it is the only method of tire repair sanctioned by every tire manufacturer and related trade organization. The use of a repair unit without a rubber stem, or vice versa, is incorrect. There is much more, however, to the officially accepted method of tire repair than the installation of two components.
The technician must first determine if a proper repair can even be made. For this to be the case, the injury has to be in the crown of the tire (or center of the tread) 1 to 1.5 inches from each shoulder (or tread edge). If the injury falls outside of these parameters, it will have to be considered as a candidate for a section repair,which can only be performed at a full-service facility. (These are industry standards for which there are legitimate reasons – he’s not just trying to sell you a new tire.) The service tech must also inspect the tire inside and out for any other forms of damage that might preclude its further safe service.
Then the injury must be probed, any foreign material removed, and the angle of penetration determined. Next, your tire repair person will select the proper repair unit to be used based on the size of the injury, center it over the hole and circumscribe its perimeter with a tire crayon. Now the tech will clean and scrape the repair area inside the crayon mark, making sure all the mold lubricants and other contaminants are removed.
 He will then remove the damage in the injury from inside the tire with a carbide cutter, running it through the hole three to five times. He’s not doing this to make the hole bigger; he’s doing it to trim the loose steel back to solid rubber. And he’s doing it with a low-speed, 1200 RPM maximum drill because a faster tool would scorch the rubber and affect its ability to adhere to the repair materials. He will also drill the hole likewise from the outside before proceeding to the next step, which, assuming all the loose steel has been trimmed and there has been no scorching, is to run a cement-coated spiral probe through the injury.
Now comes the rubber stem, which the tech pulls through the hole with a special wire after he has lubricated the tip with cement. The purpose of this plug is not to stop a leak but to keep water out of the injury and away from the steel belts, which could rust to the detriment of a good casing. He’ll cut the plug off inside the tire about an eighth of an inch above the inner liner before he fires up his 5,000 maximum RPM buffer to buff the repair area and level the plug. He buffs from the right and works his way to the left in order to send most of the rubber dust away from the repair surface. When he is finished, he will have removed the mold marks and have left a velvet-like RMA #1 or RMA #2 texture to the inner liner. (It should look like the background on your Elvis painting.) Then he will brush away any loose dust from the repair area and vacuum out the lot of it from the tire.
 Next, he opens a can of what he hopes to be fresh, uncontaminated vulcanizing cement, and works a thin coat of it into the buffed area before he, being a tire man, lights up a cigarette and waits for it to dry to a dull, tacky surface. The brand name on his can of cement will be the same as that on his box of repair units since different repair material manufacturers incorporate different chemical compositions in their products, and one may not work with another. When the time comes, he will break the polyfilm backing on the repair unit and peel it halfway back, taking care not to touch or drop an ash on the cushion gum. He centers the repair over the injury and presses the exposed cushion gum with his thumb before applying a stitching tool to the center, working the tool outward while removing the backing. When the stitching is completed, he removes the transparent polyfilm from the top side of the repair. He then applies innerliner sealant to the buffed area around the repair.
The arrows on the patches, by the way, are there for a reason. Reinforced radial repair units are constructed with cords running in a single direction. When the arrows are aimed at the tire beads, the cords run in the same direction as the radial body cords of the tire. A bias repair unit on the other hand, is made with cords that run diagonally, crossing in the center. Applied correctly, these mirror the body-ply construction of a bias tire. Universal nail-hole repairs have no nylon reinforcement and can be applied in any direction. So, Mr. Truck Driver, or Mrs. Fleet Supervisor, he may not be pretty to look at, he may smoke too much, and he may use a bunch of double-negatives when he talks – and even more when he thinks – but he’s not plugging your tire; he’s repairing it properly.
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