Chapter 12

Tires and Repairing Flats

The tires are a very important part of your vehicle. A problem with your tires will likely result in poor vehicle handling, performance, and gas mileage. You should consult your vehicle's owner's manual to determine the proper tire size and inflation.

Let's talk a little about tires, how they work, and how to maintain and/or repair them. A tire does have great strength in its carcass, but without the compressed air the tire will not have any compression strength. Putting the compressed air into the tire creates tension, which allows the tire to carry the vehicle's load. However, load carrying is just the beginning. Your tires must also provide adequate handling which includes cornering, stopping, and acceleration. Your vehicle and tire manufacturers have gone to great lengths to engineer the correct size tires for your vehicle as well as the correct tire inflation, so please follow their instructions.

Front tires will wear differently from rear tires and drive tires generally differently than non-drive tires. Drive tires tend to wear more quickly in the tread center while front tires wear more quickly in the shoulder area. A front wheel drive vehicle's front tires generally will wear much more quickly than its rear tires. Tires are generally considered worn out and must be replaced when the tread depth across two adjacent grooves is 2/32 of an inch. Sometimes only the shoulder is worn while the center still has some tread or vice versa. These tires must still be replaced.

Generally, all four tires on a vehicle are matched and even certain vehicles with different size tires will have the same size on the front and the rear. It is important to rotate your tires to ensure even tread wear and long life. Consult your vehicle's owner's manual or your local tire retailer for specifics regarding your vehicle and its tires. However, generally rotating tires every 6,000 miles should be fine.

There are several different rotation patterns, which should include the spare tire if your vehicle is equipped with a full size one. Generally, any rotation pattern is better than none at all. Be cautious of certain tires (generally high performance) which must always be rotating in the same direction. These single direction tires must be removed from the rim and remounted the opposite way when being rotated to the other side of the vehicle. Custom wheels and different front and rear tire sizes can also present rotation problems. It is a good idea to mark the tires and keep accurate records regarding rotation to ensure that each tire eventually is mounted in all wheel locations.

When purchasing new tires it is generally a good idea to get an alignment as well as have each tire and wheel balanced. Alignment is discussed in Chapter 6.

Balance refers to a state when a tire and wheel have all their weight equally distributed while spinning. If your wheels and tires are not properly balanced you may notice vibration in your vehicle's steering as well as a tendency for your wheels to wobble and shake.

With the tire mounted on the rim, balancing is performed by placing the rim on a special machine which rotates the rim at high speeds. The balancing machine will detect the imbalanced areas. Wheel weights are then attached to the rim to correct the imbalanced condition.

We discuss changing a flat tire using the spare in a separate section, but here we discuss getting the flat tire repaired. When a tire gets punctured or injured in any way, performance can be affected. Therefore, proper repair is so important. To properly repair a tire it must be removed from the rim so it may be repaired from the inside and outside. A patch must be firmly adhered to the inner liner and a plug must be inserted from the outside to completely fill the injury or puncture and seal the tread surface.

Some tire dealers will take a shortcut and not remove the tire from the rim. They will simply insert a plug into the tire. This may compromise tire life and performance. If your tire dealer suggests this type of repair insist that they do the complete inside and out repair or go somewhere else. Many tire dealers will fix a flat for free on a tire they sold you. This is only a good service if they perform the repair correctly.