Tires are required to come with information on the week and year that particular tire was made. When you are ordering your new tires, save your receipts and use them to help enforce your tire warranty, which is usually good for four years from the day you ordered your tires. Otherwise, the warranty is only good for five years based on the tire's manufacturing date. If you buy a tire that is a few years old when you purchase it new, your warranty won't expire until four years from the date on the receipt regardless of what the manufacturing date may be. This can really work to your advantage!