here are the instructions i was told step 1 Locate the DOT numbers on the sidewall of the tire. These numbers always start with the letters DOT, which stand for Department of Transportation. Step 2 Check both sides of the tire. You will notice that one number has four extra digits to it on the end. Step 3 Determine which side of the tire has the longer DOT number and read the last four digits of that number. That is the tire stamp date. Step 4 Decipher the tire stamp date using this easy formula: 0108 would indicate that the tire was manufactured in the first week of the year 2008; 1208 would indicate the tire was manufactured in the 12th week of the year 2008. This formula applies in a two-digit format to start the number of the week it was made, starting with 01 and ending with 52. The last two digits of the number indicate in which year the tire was manufactured, starting with 00 for the year 2000. There's a slightly different format for tires manufactured prior to the year 2000, but since those would be over nine years old, it's a pretty safe bet to assume they're beyond their expiration date. It might not hurt to find out if the tire you're looking at has a manufacturer's expiration date, if applicable, and determine whether that would expire before the tread wear of the tire being used on your vehicle would.