Tires: DRY ROT TIRES, 4 digits, dot code


Question
4 TIRES WERE PURCHASED IN 1997 FOR A PACE TRAILER, THEY ARE CRACKING AND DRY TOTTING.  THE INFO ON THE TIRE IS ST205/75D-14 0705, DOES THIS MEAN THE STORE HAD THEM FOR 2 YEARS BEFORE I PURCHASED THEM. WHAT CAN I DO?

Answer
James,

Recent bulletins from the tire industry indicate that tires degrade simply due to time.  The age of a tire is important even if the tire is unused.  There some disagreement over how to best express this age limitation, but my take is:

If you live in a hot climate (AZ, CA, NV, TX, and FL) then the limit is six years.  If you live in a cold climate (MN, ND, WI, MT, etc), then the limit is 10 years.  States in between are  ..... ah ........ in between.

Clearly your tires are more than 10 years old.  Further, you haven't yet identified the date of manufacture.

Here's how to tell how old the tires are:

First locate the letters "DOT" on the sidewall of the tire.  Nearby will be the DOT code.  DOT codes are 10 to 12 digits long.  BTW the digits can be numbers or letters.

The first 2 digits are a code for the manufacturing plant.  

The next 2 digits are a code for the tire size.  

The next 3 or 4 digits are a code for the type of tire.  

The last 3 or 4 digits are the date code.  The format is week/week/year/year or week/week/year.  These are always numbers.

Starting in the year 2000, the date coding used was 4 digits.  That means the largest number you should see for the year is 09.  Before 1999 the format was 3 digits.  1999 and 2000 are transition years, so you will find both 3 and 4 digits.

The date code only has to be on one side – and it is permissible for there to be a partial DOT code, so long as one side has the complete code.

If the tires were purchased in 1997, they would have a 3 digit date code.