Most people judge their vehicle’s tires by a common sense set of parameters: Will they be safe from blowouts and tread separations? Will they be rugged enough to deal with potholes and other road hazards? Will they have sufficient traction in rain or snow? And the easiest to measure: Will they last long enough so I don't have to shell out a bunch of money for new ones before a reasonable amount of time?
Increasing tire life
You can do several things to increase your vehicle's tire life. Your driving habits are most important; if you burn rubber, you're burning money. Proper tire inflation is also important, and another way to really help extend the life of your tires is a well-thought-out plan for regular tire rotation.
Why rotate tires?
Rotation means you are changing where the individual tires are mounted on the vehicle. Let's assume you have a front-wheel drive car with all four tires the same size. Each tire will carry a different load and be faced with different situations. The front tires will carry more than 60 percent of the car's weight, are responsible for putting the power of the engine to the road and handle all the steering. Finally, they are responsible for about 80 percent of the braking.
Tire rotation schedule
To make the entire set wear at the same rate to equalize tire wear and maximize tire life you can rotate them. With some vehicles, the owner's manual will have a recommended tire rotation schedule and a diagram of the rotation. A typical schedule may call for rotation every 5,000 miles with a pattern that's sometimes called "cross-rotation." In a cross-rotation, the front tires are moved to the opposite sides of the rear right-front to left-rear, left-front to right-rear and the rear tires moved straight forward. If you follow this through, eventually every tire will have been to every spot on the car, and then it starts all over again.
Tire rotation tips
There are a couple of points to remember about rotation. First, while it's easy and quick to use an air-powered impact wrench to take the wheels off, the wheel nuts or bolts should not be tightened with the impact wrench because they'll be too tight. You may have a flat tire eventually and have to manually remove the nuts that somebody else hammered on with an impact wrench. Instead, the nuts or bolts should be tightened with a torque wrench to the manufacturer's specifications. If you don't know the correct setting, any reputable tire shop should be able to help.
Second, many manufacturers recommend what are called "differential tire pressures," in which the fronts and rears are inflated to different pressures. Since different tires carry different loads, this only makes sense, but you'll have to reset the tire pressures when you rotate them to make them correct.
Here's one tip for setting tire pressures: Do it when the tires are at ambient temperature, and in the cooler part of the day. Performing this task in the early morning is a good idea. Once the day warms up, the pressures will increase as the air in the tires gets hotter. In the summer, for example, as the sun comes up and warms the tires on one side of the car, they can easily gain two or more psi over the ones on the other side still in the shade. If you set the pressures when everything is already hot, then when things cool back down the tires will be significantly underinflated, which is dangerous.
So, apply common sense, pay attention to the rotation schedule, tighten the nuts or bolts with a torque wrench and use a good tire pressure gauge, and those tires will pay you back with the longest life possible.