HIGH PERFORMANCE TIRES

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The need for speed

vehicle with all-season tires. Torque is important on every vehicle, but the forces applied to a performance tire and wheel assembly require extra attention.

If the mating surfaces are not clean, the components are damaged or worn and/or the wheel is not properly seated on the hub, the most expensive torque device in the industry will not prevent the wheels from becoming loose.

Torque is a measure of twisting force — nothing more. Clamping force holds the wheels on the vehicle and it cannot be measured in the field. The only way to approximate the correct amount of clamping force is to control the torque and the conditions of the bolted joint.

TIA’s RIST procedure is the recipe for clamping force and it should be followed every time a wheel is installed.

As far as achieving the correct torque is concerned, the most common device is a standard clicker torque wrench. By turning the handle, the technician creates tension on a spring that causes the wrench to emit an audible click when the torque setting is reached.

In order to ensure the torque is properly applied to the lug nut, the technician should apply slow and steady pressure to the handle on the end of the wrench. When the click is heard, the pressure must stop. Bad technique — where the technician continues to apply force after the click — results in an over-torque situation. Even the slightest amount of pressure after the click can increase the torque by as much as 20 to 40 footpounds if it is enough to move the nut in a tightening direction.

Since a torque wrench is a precision instrument and accuracy depends partially on the condition of its internal mechanism, the tension on the spring should be released at the end of the day at a minimum. If the spring is kept in constant tension, it will eventually start losing accuracy.

Torque wrench manufacturers recommend relaxing the tension to the lowest setting on the wrench when not in use to maintain the long-term tension in the spring. Regular calibration in accordance with the torque wrench manufacturer is another box that must be checked in the event of a loose wheel. It won’t matter until it does.

Repair advice

Finally, any discussion on performance tires must include the topic of tire repair. Like most aspects of performance tire and wheel service, the step-by-step repair process for a performance tire is exactly the same as a standard all-season tire.

Puncture repairs are still limited to the crown area; shoulder and sidewall repairs are not allowed and the maximum size is 1/4-of-an-inch.

One-piece combination repair units have a maximum angle of 25 to 35 degrees, depending on the manufacturer, while the two-piece system does not have any angle limits as long as the damage is limited to the repairable area.

For passenger and light truck tires, puncture repair procedures are universal regardless of the application.

Performance tires are different because they often have H speed ratings or higher. In some cases, the manufacturer does not recognize the speed rating after a repair and in others it does.

Some manufacturers place a limit on the number of repairs and their proximity to each other. In many cases, the tire manufacturer and the repair material manufacturer will have different limits in terms of the maximum number of repairs and proximity. From the legal perspective, the tire manufacturer guidelines always take precedence over the repair material manufacturer.

As discussed earlier, speed rating in North America is more like a performance rating that indicates how the tire will handle. The actual top speed should not be a factor because there are no roads that have unlimited speed limits. I recently purchased a 2017