http://www.1010tires.com/tech.asp?type=tires_general#sizingDOT stands for Department of Transportation. The 10, 11 or 12 digit code appearing after the DOT designation gives information such as the week and year the tire was produced, as well as the manufacturer, plant, tire line, and size. The first 2 characters designate the tire's manufacturer and plant code. The third, fourth and fifth characters, are the tire size code. The last three or four numbers (4 numbers for years after 2000) are when the tire was manufactured. The first two digits of the date code represent the week and the last 1 or 2 digits represent the year.