The Department of Transportation's tire registration is a way to file your tire's unique ID code in case of a safety issue or factory recall. Tire companies in the United States have created online registration tools that take and store product information and customer details in a database in case there are any nationwide issues.
The DOT implemented the registry as a result of safety concerns stemming from investigations around tire failure like the Explorer/Firestone case in August 2000. The case focused on 40 deaths caused by tires shredding on Ford Explorers during highway travel, and it resulted in the recall of 14.4 million tires.
The Firestone tires in question were part of the original equipment on Ford cars from 1991 until 2000, when the safety defect was discovered.