|The DOT marking on the sidewall shows the week and year the tire was made.|
|This ambulance tire blow out was found during a station call when the crew complained of a right inside rear tire that was low.|
Recently, a local fire department was asked to perform an internal cost savings survey for its fleet services bureau. While looking at all the potential direct and indirect cost savings, it became clear that one of the largest operating costs for the fleet was tires.
Since the tires on all emergency vehicles are one of the largest fleet costs, they should be viewed as assets, not consumables. Consumables refer to merchandise that is bought and consumed. Truck tires should be treated as assets, which are tracked and managed from the time of purchase to retreading to ultimate disposal.
Every fleet should implement some type of tire management program. Remember that tire technology has advanced over the years. There are newer tire compounds, computer software for tracking, inflation gauges and other tools that can help manage your tire program.
One of the first steps is to determine where the rubber meets the road by considering the type of application, weather, terrain and weight to select the best tire for the job. While new technology is available for tire management, your program can still be successful the old-fashioned way – with pencil, paper and a regular tire gauge. What’s important is having a program.
When implementing a tire management program, make sure to include the most current NFPA 1911 Standard for the Inspection, Maintenance, Testing, and Retirement of In-Service Fire Apparatus, which is the 2007 Edition. When it comes to tires, follow the information in Chapter 7, which includes:
- Section 7.3.3* Tires shall be inspected for damage and shall be inflated to the tire manufacturer’s recommended pressure.
- Section 7.3.4* Tires shall be replaced at least every 7 years or more frequently when the tread wear exceeds state or federal standards as determined by measuring with a tread depth gauge. [See 6.3.1 (4).]
Keeping tires properly inflated is foremost. No one can just look at a tire and tell whether it has the correct inflation pressure. The tire program should include targeted pressures for tires based on the weight of each axle; calibrated air pressure gauges and having someone check tire pressures on a weekly basis.
Check The Data Plate
It is vitally important that you look at the tire manufacturer’s data book to properly inflate the tire in accordance to the application and individual axle weight. While the tire sidewall has a maximum tire inflation pressure, it is imperative to first weigh the front and rear axles individually and then look at the tire data book, which can be obtained from the manufacturer or from the manufacturer’s Web site.
To obtain the tire size and weight rating, check the truck manufacturer’s data plate, usually on the driver’s doorjamb, and look at the information provided. Based on the axle rating, the data plate notes the proper tire inflation for the front and rear tires. Compare that information to the sidewall of the tire, the certified weight of each axle and then analyze all of that compiled information and compare it to the tire data book with the spreadsheet that includes ratings for that tire.
The bottom line on inflation is that you cannot run under the minimum pressures required to support the axle load, and you should not run the tire over the maximum pressure listed on the side of the tire. The high cost of overloading or over inflating or under inflating is:
- Reduced handling, a safety issue.
- Longer stopping distances, a safety issue.
- Rapid tire wear, a cost issue.
- Rapid component wear to bearings, springs, steering and wheels, a cost issue.
- Excessive fuel consumption, a cost issue.
- Tire failures, safety and cost issues.
A Tire’s Footprint
When looking at the tire structure and application, including weight versus tire pressure, understand that each tire makes a certain footprint on the road. With that in mind, it’s imperative that the proper tire pressure is reached because over inflating or under inflating will change the footprint. Incorrect tire pressures will distort tire performance, causing the tire to work harder, increasing the potential for tire failure and increasing fuel usage. Under inflation by as much as 20 percent can decrease the tire life by 30 percent.
Invest in a $15 tire gauge to properly check each tire for the correct pressure, and that will pay tremendous dividends.
Other strategies can be implemented to improve tire performance and longevity. Look at proper total vehicle alignment and check shock absorbers. Rather than just inspecting tires for nails or screws, make sure to look for uneven tire wear that will indicate improper toe and camber. Make sure that the technicians performing regular maintenance are trained to look for uneven tire wear that can indicate other problems with the vehicle.
When the firehouse crews wash the trucks, they help reduce the wear on the tires. Washing tires with warm soapy water helps eliminate premature aging and deterioration of the rubber due to contaminants on the road. The magnesium-chloride sprayed on the roads in the winter season can affect the rubber on tires, as well as aluminum and electrical components. In addition, any petroleum-based products, such as fresh oil used on newly paved roads, leaking oil seals or oil on the firehouse floor can cause tire deterioration.
Chapter 6 of the NFPA 1911 standard addresses deficiencies that should cause an apparatus to be taken out of service, among them problems related to chassis, axles, steering and suspension systems, drivelines, wheels and tires.
For example among deficiencies specified by the standard are:
- Tires with cuts in the sidewall that penetrate the cord.
- Tires that have a tread depth of less than 4/32 inch on any steer axle or 2/32 inch on any non-steering axle at any two adjacent major tread grooves anywhere on the tire.
- Wheels or rims with bent, broken, cracked, improperly seated, sprung, or mismatched lock or side rings; cracked, broken or elongated bolt holes; and loose, missing, broken, cracked, stripped, or otherwise ineffective fasteners.
Take time to sit down and read the NFPA standard in its entirety. Some sections include asterisks, which signal that additional explanatory information is in an annex to the standard.
While the big three most notable tire manufacturers (Michelin, Goodyear and Bridgestone) produce quality products, there are other tire makers (for example, Continental, Cooper and Yokohama) that have taken tremendous strides and make very good tires that can reduce fleet costs. It will pay off to do your homework when making tire purchases in order to marry safety and value.
Whether you have five trucks in your fleet or 500 it is important to look at the total cost of tire ownership as more important than the original purchase cost. It is critical to get the right tire for the right application. A tire management program combined with proper vehicle maintenance, inspections and repairs, along with educating engineers and technicians about tire performance, will have a huge impact on your bottom line with a healthy return.
Editor’s Note: Brian Brown is bureau chief of fleet services for the South Metro (Colo.) Fire Rescue Authority. He has over 30 years’ experience in fleet services, with more than 20 years in fire apparatus fleet services, and is a former president of the Colorado Fire Mechanics Association. His certifications include Master Automobile Technician, Master Medium/Heavy-Duty Truck Technician, Emergency Vehicle Fire Apparatus Technician Level I and Level II, Emergency Vehicle Technician Management I, Fire Fighter II, Fire Instructor I and Hazardous Materials Responder Technician.