Tires are one of the most important components on a vehicle. They act as the contact points with the road surface to provide the forces needed to start, turn, and stop the vehicle.

Tires are also probably one of the least-maintained components on a vehicle. That's too bad, because basic tire maintenance is simple and takes only a few minutes to perform.

Regular Tire Maintenance

Regular tire maintenance should be part of a department's preventive maintenance program as specified in NFPA 1915. The same inspection and maintenance procedures should be applied to both original tires and recapped tires because both types are subject to the same wear, heat and other factors.

Tire maintenance checks should be made daily for fire apparatus that see a lot of service, or at least weekly for apparatus that respond less frequently. Here are some things to look for:

1. Tire pressure. Ideally, the pressure in every tire should be checked with an accurate gauge to ensure it is within the maximum and minimum specified by the tire manufacturer. You may have to install stem extenders on the inner tires of duals to reach them easily. The apparatus should not have been driven recently, and the tires should be cold. Many medium-duty and heavy-duty truck tires have minimum pressures of about 60-70 psi. Light-duty truck tires have minimum pressures of about 30-40 psi. Always check the manufacturer's recommended minimum pressure for the tires on your apparatus. Any tire with a pressure below the minimum should be considered flat and should be inspected for possible leaks. This will usually involve taking the apparatus out of service. If you use a tire "thumper" instead of a pressure gauge, be sure to double check the pressure with a gauge occasionally to make sure your ear is still calibrated.

2. Valve stem caps. The valve stem on every tire should have a cap. Replace any caps that are missing or damaged. Without a cap, the spring-loaded valve stem core can become clogged with dirt and mud, which can erode the stem seal or block the stem in a partially open position and cause a leak. A plugged stem can also make it difficult to take a pressure reading.

3. Tire damage. Tires should be inspected for damage. Look at both the tread area and the inner and outer sidewalls. An inspection mirror helps. Nails, bolts and other foreign objects should be removed before they penetrate the liner and cause the tire to separate.

4. Tire wear. Learn to recognize the signs of uneven or excessive tire wear. This can be caused by improper wheel alignment, improper axle alignment, improperly matched dual tires, or tire and wheel imbalance. In most cases, you should have a tire shop resolve these problems.
   

Dealing With Serious Problems

Basic tire maintenance should also include knowing what problems are serious enough to take the tire -- and the apparatus -- out of service. The NFPA 1915 preventive maintenance standard offers three out-of-service criteria for tires: tires with cuts in the sidewall that penetrate to the cord, tires that are defective and tires that have a tread depth of 4/32-inch or less on the steering axle or 2/32-inch on any non-steering axle. Tread depth should be measured at any two adjacent major tread grooves anywhere on the tire.

Other conditions you can add to the out-of-service list include flat tires, tires with audible leaks and tires with embedded objects. Be especially aware of tires that produce noticeable vibration or that have bulges, bumps or other unusual conditions. This signs can indicate a serious problem and may result in sudden tire failure.

How to Estimate Tire Life

Fire apparatus and other emergency vehicles can keep the same set of tires for their entire lives, or they can literally run the tires off the rig in a year or less. Every situation is different, and monitoring the tread depth is the best way to determine tire life.

As a rough rule of thumb, one apparatus manufacturer says that most fire apparatus tires should last about 20,000 to 25,000 miles. Again, the tread depth should be monitored. Rear-steer apparatus may wear the rear tires in as little as 9,000 miles. Lighter weight apparatus, such as quick attacks, light rescues and ambulances, usually get driven harder and may wear the tires down in 7,000 to 12,000 miles.

Finding Help

Contact your local truck tire dealer for information about tire inflation pressures, proper maintenance procedures and specific tire problems. You can also visit the following truck tire manufacturers' Web sites:

Bridgestone/Firestone: http://www.trucktires.com
Michelin: http://www.michelintruck.com