You've Must Know the Date the Tire was Born
By Billy Edwards
Tire aging on cars has received attention recently, but I haven’t seen much of this information directed to motorcycle riders. One reason may be that m-motorcycle tires wear out much quicker than car tires – while a drive may rack up as much as 50,000 miles or more on car tires, we motorcyclists typically get 7,000 - 10,000 miles on our motorcycle tire. So for some, the motorcycle tire may not last long enough – from a chronological age standpoint – to worry about.
But … many of us may not put that much mileage on our motorcycle tires if the motorcycle is not our primary vehicle (you know, it’s just hard to take the kids to Grandma’s on a motorcycle), so it may take several years. Additionally, we generally don’t know the age of the tire when it’s put on our bike. This isn’t to say your dealer sold you a used tire instead of a new one. It’s just that from a tire aging standpoint, the tire begins to age as soon as it is born, which is when it comes out of the vulcanization press at the tire plant.
Basically, exposure to oxygen, ultra violet light (sun light), heat, and use all work to break down, wear out and harden the rubber compound used in the tires, whether the tire is on a bike or not.
How Old is Too Old?
So how old is too old? Well, it seems that there’s some debate about it. Some say ten years, some say six years. Some car tire companies and most safety advocates go with six years. Unfortunately, tire aging information from the tire companies is hard to come by. I’ve looked on both the Dunlop and Metzler motorcycle tire websites and I don’t find any information about tire aging.
For me, I’m going to stick with the 6-year guideline as a hard line, and if I’m somebody who likes to ride on the highways at highway speeds (and I am), I’m going to start getting uncomfortable at about three or four years.
Now that you’ve decided on your age limit, how do you determine how old your tire is? And the answer ain’t the date you bought it. You’ve gotta know the date your tire was born.
Tire Birthdates
If the tire was manufactured since 2000 or later, the last four numbers represent the week and the year the tire was made. In the case of the tire pictured, the numbers are 3505.The first two numbers are the week the tire was manufactured (the 35th week) or the last week of August. The last two digits are 05, which is 2005.
(To figure which week, divide by 4.3. Nailing it to the exact week isn’t necessary – if you get the correct month, or even within a month of the correct month, a tire is probably going to be OK as far as age goes. In other words, running it 6 years or running it 6 years and 1 month isn’t that much difference.)
Amaze Your Friends
Hopefully, nobody’s riding around on tires more than six years old, so information about tires older than 2000 isn’t necessary. But, just to be complete: tires manufactured during the 1980s had a three-digit code for the date, with the first two digits indicating the week, and the last digit indicating the year (355 would mean the 35th week of 1985) and tires manufactured in the 1990s had a three-digit date code but with a little triangle (Δ) after the code. So don’t ride on a tire from the 1980s or 1990s, but now you can amaze your friends by telling them exactly how old the tire is in the old tire swing in the back yard.
Also see this post...
Harley Davidson Community
By Billy Edwards
Tire aging on cars has received attention recently, but I haven’t seen much of this information directed to motorcycle riders. One reason may be that m-motorcycle tires wear out much quicker than car tires – while a drive may rack up as much as 50,000 miles or more on car tires, we motorcyclists typically get 7,000 - 10,000 miles on our motorcycle tire. So for some, the motorcycle tire may not last long enough – from a chronological age standpoint – to worry about.
But … many of us may not put that much mileage on our motorcycle tires if the motorcycle is not our primary vehicle (you know, it’s just hard to take the kids to Grandma’s on a motorcycle), so it may take several years. Additionally, we generally don’t know the age of the tire when it’s put on our bike. This isn’t to say your dealer sold you a used tire instead of a new one. It’s just that from a tire aging standpoint, the tire begins to age as soon as it is born, which is when it comes out of the vulcanization press at the tire plant.
Basically, exposure to oxygen, ultra violet light (sun light), heat, and use all work to break down, wear out and harden the rubber compound used in the tires, whether the tire is on a bike or not.
How Old is Too Old?
So how old is too old? Well, it seems that there’s some debate about it. Some say ten years, some say six years. Some car tire companies and most safety advocates go with six years. Unfortunately, tire aging information from the tire companies is hard to come by. I’ve looked on both the Dunlop and Metzler motorcycle tire websites and I don’t find any information about tire aging.
For me, I’m going to stick with the 6-year guideline as a hard line, and if I’m somebody who likes to ride on the highways at highway speeds (and I am), I’m going to start getting uncomfortable at about three or four years.
Now that you’ve decided on your age limit, how do you determine how old your tire is? And the answer ain’t the date you bought it. You’ve gotta know the date your tire was born.
Tire Birthdates
Here the U.S. Department of Transportation comes to the rescue with its Tire Identification Code, stamped into every tire as it’s manufactured. The code is a combination of numbers that identifies the manufacturing location, tire size, manufacturer's code, and week and year the tire was manufactured. You can find the code on the sidewall of the tire, like the one pictured below.
(To figure which week, divide by 4.3. Nailing it to the exact week isn’t necessary – if you get the correct month, or even within a month of the correct month, a tire is probably going to be OK as far as age goes. In other words, running it 6 years or running it 6 years and 1 month isn’t that much difference.)
Amaze Your Friends
Hopefully, nobody’s riding around on tires more than six years old, so information about tires older than 2000 isn’t necessary. But, just to be complete: tires manufactured during the 1980s had a three-digit code for the date, with the first two digits indicating the week, and the last digit indicating the year (355 would mean the 35th week of 1985) and tires manufactured in the 1990s had a three-digit date code but with a little triangle (Δ) after the code. So don’t ride on a tire from the 1980s or 1990s, but now you can amaze your friends by telling them exactly how old the tire is in the old tire swing in the back yard.
Also see this post...
Harley Davidson Community
