Rohlwing: The truth about tire repairs

In the trucking business, there are several unavoidable events. From tailgating and tolls to traffic jams and detours, moving freight is not without its challenges.

Truck tires also have certain inevitabilities, such as the dependence on inflation pressure, alignment, and properly adjusted brakes. Like death and taxes, they are truly unavoidable.

Truck tires are subject to events that cause damage. Severe impacts causing instant deflation will send them straight to the scrap pile, while puncturing objects cause varying degrees of air loss that may or may not be repairable. In either case, a tire professional will ultimately decide whether the tire needs to be replaced or repaired.

The main types of truck tire repairs

Truck tire repair is divided into three categories: puncture, reinforced shoulder, and section. Puncture repairs are installed when the injury is 3/8 inch or less and located in the tire’s crown area. The crown is the center of the tread, about 1 to 1.5 inches in from each shoulder. These are easy to install, common, and very reliable when procedures are followed. Reinforced shoulder repairs are similar to puncture repairs in terms of process, but a larger repair unit is required to prevent it from being anchored in the flex zone of the sidewall. These repairs also require greater precision. Section repairs represent major surgery for truck tires and can accommodate larger injuries in the tread, shoulder, and sidewall.

It’s also important to note that technology has created the most advanced repair systems in the history of tires. The ultimate goal is adhesion, and modern repair units bond so effectively that when properly installed, attempts to remove them would tear the tire’s innerliner. Most repair failures result from failing to follow procedures and guidelines.

How technicians ensure safe tire repairs

The basic principles of tire repair are to remove the damage, fill the injury channel to prevent water from entering the casing, and then seal the innerliner to prevent air loss. Removing the damage is a key component, as truck tire casings are composed of steel cables in the body plies and the belt package. When an object penetrates the tire, those cables are broken. As the tire flexes, the cables begin to unwind, leading to separation. That’s why patch-only repairs are not recommended, even for the smallest injuries. Technicians are not “making the hole bigger” when they use a carbide cutter to drill the injury. They are removing the damaged cables to stabilize the area around the injury.

Filling the injury for a puncture or reinforced shoulder repair requires a cured rubber plug or stem. Chemical vulcanizing cement is applied to the injury channel and the stem to create a permanent molecular bond with the tire. When properly installed, water cannot enter the casing. Section repairs fill the void with uncured rubber that becomes permanent when heat and pressure are applied for a specific period of time. Like a rubber stem, it bonds at the molecular level when properly installed.

Sealing the innerliner to prevent air loss requires a repair unit. Puncture repairs in the crown area can use rubber-reinforced or fabric-reinforced repair units because there is minimal flex in the center of the tread. Reinforced shoulder and section repairs require a fabric-reinforced repair unit to withstand sidewall flexing and provide additional stability in the area where the damaged body plies were removed. After buffing the innerliner to create a uniform surface, vulcanizing cement is applied to permanently bond the repair unit to the tire.

Properly repaired truck tires are safe for fleets

Thousands of truck tires are successfully repaired every day by service providers and retreaders. The failure rate is significantly less than 1% when proper procedures and guidelines are followed. When repairs actually do fail, it is almost always traced back to technician error. In other words, the most important factor is who repaired the tire.

Many truck tires are scrapped prematurely because the fleet has lost confidence in the repair process. In many cases, it takes just one bad experience for management to ban repairs altogether. There’s no need to fear tire repair if you know who is installing the materials. If industry guidelines for inspection and installation are followed, fleets can be confident that the tire will be safely returned to service and that the casing will be preserved for retreading.