I just heard again, someone saying they were harassed because of this tire expiry thing... and had to lookup this.


Determining the age of a tire is an important factor to consider in maintaining the quality and safety of a vehicle. Until a tire shows visible signs of deterioration, most motorists consider it useable. However as tires age, their quality decreases as a result of weather, storage conditions, and usage. In fact, studies have proven that the rubber components in tires have a tendency to dry up after 6 years, even if they have never been used. This deterioration increases the risk of a malfunction such as a flat-tire or blow-out that would decrease the overall operational safety of your vehicle. Although it is impossible to pinpoint an exact expiration date, as a general rule, all tires (even your spare ones) should be replaced after 10 years from the date of manufacture.
If your tires appear to be in good condition and you are unsure of their age, you can always refer to the sidewall of the tire to find the date the tires were manufactured. The Department of Transportation (DOT) requires Tire Identification Numbers (or Tire Serial Numbers) to be included on each tire. These codes consist of the letters DOT, followed by a series of numbers and letters. For tires that were manufactured after the year 2000, the last four numbers of the code will identify the week and year in which the tires were manufactured. For example, the following identification number indicates that the tires were manufactured in the 51st week of the year 2008: DOT CX8J 3C2 5108. For tires that were manufactured before the year 2000, the date will be represented in the last three digits of thfe tire. For example, the following identification number indicates that the tires were manufactured in the 40th week during the 8th year of the decade (1998): DOT U2LL LQLR 4088.
If you are still unable to determine the age of your tires, consult a professional technician who will be able to tell you when or if your tires need to be replaced

http://m.tires.canadiantire.ca/mt/tires.canadiantire.ca/en/info-centre/tireAge?request-uri=tireAge