The Author of this book was looking at a 3 year old vehicle

when he noticed that the Right Rear tire had a build date code

newer than the vehicle.

He asked the Owner, "How badly was the vehicle hit ? The Owner

stumbled and shuttered a little, then said,"How did you know that

an accident occurred ?" He told the Owner that the Right Rear

tire, while being the same exact tire as the others, had a date 

code indicating that it was only One year old, whereas the original

tires were the same age as the vehicle.

The first "2" numbers of the DOT code on the Tire indicate

 the week of the tires Manufacture and the last "2" digits

of the FOUR Digits indicate the Year the tires are manufactured.

The Owner immediately admtted that the vehicle slidon ice and

hit a Curb , damaging the Right Rear Tire and Wheel Rim. Both

the Tire and Wheel Rim were replaced and the Alignment checke.

The Owner then dropped the price of the vehicle $500 !

Knowing the Date Code help assure that Fresh Tires are purchesed.

It also helps Techs and  Vehicle Owners determine if the Tires have

been replaced.

Automotive Principles Techology - James D. Halderman   (1999 Edition)

https://www.sokule.com/blog/cbarkwell