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Many members will be taking to the road this summer, in their Classic Thunderbirds, to attend the various regional conventions and some will be driving several hundred miles. The T’Bird maintenance item most often overlooked for the trip is the age of the tires. Collector cars are not used daily and in some cases the tires have very few miles, this coupled with the fact that they still look new, we tend to not consider their age.
Rubber products start to slowly deteriorate shortly after they are manufactured. The Department of Transportation (DOT) requires all tire manufactures to serial number and date code all tires. These numbers are found on the exterior tire sidewall facing the underside of the car.
DOT and the National Highway Traffic Safety Administration (NHTSA) requires that the tire identification code be a combination of eleven or twelve letters and numbers that identify the manufacturing location, tire size, manufacturer's code plus week and year that the tire was manufactured.
Currently the week and year the tire was manufactured is contained in the last four digits of the serial number, with the first two digits identifying the week the tire was manufactured immediately followed by two digits used to identify the year.
Example XXXXXXXX 4800, 48 indicates the week of the year, 00 indicates the year 2000. If the date was 4801 it would be the 48th week of 2001.
Tires manufactured prior to 2000 have a three digit date code. For example: 422 Indicates the 42nd week and the 2 represents 1992. This tire would be considered unsafe even as a spare.
Ford Motor Co as well as other car manufactures added a 6 year Tire replacement recommendation, regardless of tread wear, to its website and all 2006 Owners Manuals.