Tire Safety: Expiration Dates

Ag Safety and Health October 26, 2016 Print Friendly and PDF

Imagine cruising down the road on a beautiful spring afternoon or returning home after a long day at work when suddenly the back right tire of your vehicle explodes. Luckily, you maintain control and safely maneuver to the side of the road. The tires are new, purchased a few months ago from a local tire shop. How could this happen to new tires?

The fact is that all tires have an expiration date. Surprisingly, many consumers and sellers of tires do not know about tire expiration dates. An uninformed consumer thinks he or she purchased brand new tires when in reality those tires may have been sitting on the shelf for years. Even though the tires were never used on a vehicle, they are still several years old. Every tire has a birth date—the day it was manufactured—and an expiration date that is six years from that manufacture date. Most automobile manufacturers warn drivers to replace vehicle tires after six years. To wait any longer than that is a gamble with tire integrity and is risky for drivers.

So what can you, as a driver, do to protect yourself? When buying new tires, ask for the newest tires available, and look at the tire’s manufacture date. The manufacture date is a Department of Transportation (DOT) code of 10 or 11 characters embossed on the inside of the tire (see Figure 1). For new tires, the code is always 11 characters. However, tires manufactured before the year 2000 have a 10-character code. Expiration dates for tires manufactured before 2000 were based on a 10-year scale because the expected life-span of a tire was 10 years. Current guidance suggests that tires should be expected to last a maximum of only six years.

Tire Code Photo

Figure 1. A tire manufactured-date code, shown in the yellow box, may appear on the outside of some tires. The 11-character DOT code, shown in the red box, appears on the inside of tires.

Recently, some tire manufacturers have begun to stamp partial codes on the outside of tires (facing away from the vehicle) so that checking the date does not necessitate removing the wheel. This partial code, boxed in yellow  in Figure 1, is the most important piece of information about a tire. These last four digits of the DOT code represent the manufacture date of the tire. The last two digits refer to the year the tire was produced, and the first two digits identify the week number within that year. The tire shown in Figure 1 was manufactured on the 36th week of the year 2001. That tire was on a trailer that had been sitting in a field unused for 10 years, and it showed signs of dry-rot cracking. It is unclear whether trailer tires should be replaced every six years since they do not receive the same daily punishment as automobile tires. However, automobile tires should be replaced every six years.

The majority of people who take the gamble of keeping outdated tires do so to save money. Driving on outdated tires is risky not only for the driver of the car having those tires but also for other drivers. Take the initiative and change vehicle tires every six years, or sooner, to diffuse a potentially dangerous situation.

 

Authored by:
Matt Deskevich, Student Assistant at Penn State University – mdd5309@psu.edu
 
Reviewed by:
Bill Harshman, Penn State University (Has since retired)
Dennis Murphy, Penn State University – djm13@psu.edu
Aaron M. Yoder, University of Nebraska aaron.yoder@unmc.edu
Kerri Ebert, Kansas State University kebert@ksu.edu
 

 

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This work is supported by the USDA National Institute of Food and Agriculture, New Technologies for Ag Extension project.