Handle with Care

John Baxter | May 01, 2012

3/8-inch. It must consist of a rubber stem and a patch, sometimes combined in an integral unit. The repair must be done from inside after the tire is off the rim. Manufacturer specifics must be followed.

Bridgestone’s materials also say that section repair is required for shoulder and sidewall damage, and it can’t be done on the bead. Section repair is more complex than a patch and plug, so it’s normally done by a professional. The repair must be vulcanized, meaning the use of adhesives that produce a virtual rubber weld. Such repairs are normally marked with a distinctive triangle so roadside inspectors will know the tire’s small bulge is due to a proper repair.

Maintaining balance

The most critical thing in tire balance is “concentric mounting,” meaning the tire is centered precisely on the wheel. Once that happens, balance problems tend to be minimal. “We try to make a uniform product that does not need balancing,” says Decker. “We try to minimize the amount of maintenance required for the truck owner.”

The Tire Doctor in Bridgestone’s series of “Real Questions, Real Answers” advertisements advises: “Both the tire and wheel must be clean and properly lubricated. Otherwise, the tire bead can get stuck in the wrong position on the rim flange before it is fully and concentrically seated. Improper mounting procedures, including poor cleaning and inadequate lubrication, are the most important factors.” Off-balance tires can lead to severe irregular wear. A bent axle or wheel can even result from a tire crooked on the rim, in addition to rapid wear.

When should you check balance? If you have a ride complaint, says Jones. “Before removing the tire and wheel assembly, check for radial and lateral run-out by determining if the tire is concentrically mounted. Bent wheels, improper mounting or flat spotting can cause excessive run-out.” Run-out refers to the outer surface of the tire moving in and out as it is rotated, which happens if it’s not concentrically mounted. “If foreign matter has clung to any tire or wheel, be careful not to contaminate the bead, and be sure to advise any personnel working with the tire to exercise due caution,” he adds. In other words, make sure the rim and wheel are completely clean so the tire bead can slide all the way onto the rim and won’t be pushed out.

Decker stresses the use of clean wheels in good condition. Dirt and other materials can build up on a tire stem. Hub-piloted wheels, he adds, may not mount concentrically to the hub when the centering tabs on the wheel are worn.

“When balanced with weights, a dynamic balance is preferred over a static balance,” says Miller. “Dynamic balancing means using a machine that spins the tire at road speed rpm and can indicate to the technician with a strobe light, or by other means, where to mount any balancing weights.”

 

How to de-mount and mount a tire:

Michelin’s Doug Jones recommends these tools for the job:

• A bead-breaking wedge with a handle

• A steel, rubber-cushioned tire hammer

• A wedge or bead breaker designed for the purpose

• Large tire irons with spoon ends, as well as small tire irons

• “Inflation cage” or restraining device

Used tools can develop sharp edges that will damage the delicate bead, Jones notes, so make sure the tools are in good shape.

Removal

1.  Remove the wheel and release as much air pressure as you can.

During tire work turn the wheel so the narrower of these inner bulges is facing upward.

2.  Turn the wheel onto the correct side for easy removal. Inside the rim are two bulges, one narrower than the other. If the narrower section is above the other, the wheel is on its correct side, which usually means the valve stem side is downward. However, on most 19.5-inch rims, the stem should be upward.

3.  Make a soap-and-water solution, or get a tire and tube mounting compound, and then thoroughly douse the bead on both sides to lubricate the beads. Jones suggests a vegetable-based lube mixed with proper water ratio according to the manufacturer’s instructions. “Never use antifreeze, silicones or petroleum-based lubricants,” he says.

4.  Use a tire spoon and slide hammer or rubber-coated hammer to break the bead by gently wedging the spoon between the bead and rim at one point and then operating the slide hammer to force the two apart. Pry at additional locations if necessary.

Lubing the bead is critical to getting it to slide on for concentric mounting and balance.

5.  Use a special valve stem wrench to remove the valve stem by unscrewing it and then pulling it out.