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Selection and Maintenance of Tires for Maximum Life Tom T  |
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How should you select the best tires to suit your needs? What characterizes an all-season tire? What is involved in 'plus (up) - sizing' tires? How many snow tires should you use on four-wheel or two-wheel drive? What should you do to maintain your vehicle's tires for maximum life? These are questions I get asked frequently.
When purchasing tires, let the tire experts know your driving habits so that they can suggest the best tires for your car. If you want to feel confident (and ask the right questions), learn how to read the UTQGS (Uniform Tire Quality Grading System). The UTGQS information is molded onto the sidewalls of the tires and it grades tires on three factors: Treadwear, traction, and temperature resistance.
Treadwear - This grade is based on the wear rate of a tire when tested under carefully controlled conditions. For example, a tire graded at 200 should have useful tread twice as long as a tire graded at 100. Obviously, tire life (in miles) varies depending on actual driving conditions. Variation in driving habits, service applications, attention to proper maintenance, and road conditions all contribute to treadwear.
Traction - Traction grades represent the tire's ability to stop on wet pavement as measured under controlled conditions on asphalt and concrete. The traction grades from highest to lowest are: "AA," "A," "B," and "C." Tires graded "AA" may have relatively better traction performance than tires graded "A," "B," or "C," based on straight-ahead braking tests. These grades do not reflect cornering or turning traction performance of the tires.
Temperature Resistance - This grade reflects the tire's resistance to heat and its ability to dissipate heat. Sustained high temperatures can cause decreased tire life or sudden tire failure. The grades from highest to lowest are: "A," "B," and "C." "C" grade represents the absolute minimum requirements by federal standards. This grading system is based on proper inflation, proper mounting, and the assumption that the tire's load is within its capacity.
I am frequently asked what distinguishes all-season tires. They have two major characteristics:
* A tread design that disperses weather elements (i.e.: rain, snow, mud) out from under the footprint of the tire. If you were to observe a typical all-season tread design under a slow-motion camera, you would see that it performs two functions. It squeegees the road and it pumps water, snow, and slush from under the tire's footprint, providing maximum tire-to-road traction.
* All-season tires are made of a rubber compound that doesn't freeze in temperatures below the freezing point. This characteristic is essential for the pumping and squeegee actions described above.
The big craze today is plus-sizing tire/wheel combinations. It is commonly referred to as installing "dubs." A typical dub application might be to go from a 17" tire/wheel combo to a 22" setup. This kind of setup allows you to move to a wider footprint tire with a larger diameter rim. There are two factors to consider when making this kind of a move:
* Make sure the new tire is not too wide so that it will clear critical suspension and steering components as well as the body panels. Careful measurement before installation is critical. Measure and re-measure! It could save you lots of dollars!
* Make sure the overall diameter of the new tire/wheel combo is very close to the original configuration (ideally, it should be exactly the same). If the change is too drastic, the speedometer and vehicle performance computer is affected. The computer receives critical information from speed sensors and this info is used by the performance computer to work out fuel delivery, ignition, and transmission shift strategy.
Many of you who live in winter climates often ask about snow tire applications. If you want maximum traction in snow, install snow tires at all four corners of the vehicle, giving you maximum traction in all winter conditions. On a front wheel drive vehicle, installing snow tires only on the front will cause the rear end to fish tail when cornering (the rear tires don't have the bite). On a rear wheel drive vehicle the opposite is true. On four wheel drive vehicles, four snow tires make for sure-footed traction in all winter conditions.
You spend a lot of money on tires, so to get the most mileage out of them:
* Rotation and re-balancing: This simple service can dramatically extend the life of your tires. Each tire has a different wear factor, depending on its mounted position on the car. Rotating the tires every 6,000 miles or six months gives each tire equal time at each position on the car, minimizing wear. It is important to re-balance the tires every time they are rotated. When the tire is new, it is balanced based on the mass of rubber present at that time. As the tire wears down, the rubber mass diminishes, throwing off the balance. This causes a "tramping" (or bouncing) effect as the tire rolls at highway speeds. This motion creates a choppy wear on the tread, causes tire noise, and escalates wearing. (Not to mention that it causes premature wearing of the shocks and struts!).
* Wheel alignment: Have wheels aligned every year or 12,000 miles (whichever comes first). The alignment angles in your car's front and rear end change as parts wear and poor road conditions jostle the suspension. On cars with 4-wheel independent suspension or front wheel drive, get a 4-wheel alignment. Why? Because these cars have adjustable alignment angles at each wheel that are affected by the same forces mentioned above. When the rear or front wheels get out of alignment, the tires want to track against each other. This causes pulling, drifting, dog tracking (the rear of the car tries to pass the front), and excessive tire wear.
* Maintain the tire manufacturer's recommended air pressures:: Improper air pressures can wear tires. When a tire is under-inflated, the center of the tread will "bow" inward, causing excessive wear on the outside treads. When a tire is over-inflated, the center of the tread will "bow" outward, causing wear on the center of the tire's tread. Air pressure varies with temperature, poor tire condition and load weight. So keep a regular check of tire pressures and, if you must carry additional weight, check the tire manufacturer's recommended air pressure adjustments.
* Maintain the car's suspension and steering systems: Worn suspension and steering components will wear tires. When you have the vehicle aligned, have these components checked for integrity. An alignment is only as good as the parts you're aligning!
* Maintain shocks and struts: The purpose of the shock absorbers and struts are to dampen spring oscillation. Without them the wheels would be allowed to bounce, allowing tires to wear out prematurely. In addition, wear takes place on related components.
As you can see, the right tires produce a safe, effective, and comfortable ride. Just as importantly, proper tire maintenance prevents wear and tear on more than just your tires ... and that puts money in your pocket!
'Til next time...Keep Rollin'
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 With over 27 years in the automotive industry and nearly a decade in automotive talk radio, Tom Torbjornsen makes learning about cars easy with his personal manner, his expert advice, and his high energy and entertaining style. Tom has the unique gift of simplifying the complex and tearing down the technical, meeting you at your level of understanding. You will be encouraged as you gain the confidence to deal with problems related to the second most expensive purchase you will make in a lifetime your automobile.
Email Tom
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