I have noticed on some "tires for sale" ads, the seller says he doesn't know how old they are. The following should help in determining the age of the tires.

The law requires the manufacturer to show when the tire was made. Don't know when that became effective. Since 2000 on the sidewall (usually back side) near the rim you should find the letters DOT followed by a series of letters & numbers. It is the last four numbers you want. First two will be the week of the year and the last two will be the year the tire was made. Example, 1219 would translate to the 12th week and 19 would be the year.
If the tire was made prior to 2000. It will be the last three numbers you want. Example, 329 would mean the 32nd week of 1999 or 1989 or maybe even 1979.

If no DOT number is shown it most likely means the tire is reeeealy old and the tire maybe should be bought and displayed as an "antique".

This is how I understand the method of determining the year a tire was made. If I made a mistake hopefully someone will correct the info.

Dick

Your notes accurately reflect what the NHSTA regulation requires as part of the TIN (Tire Identification Number).

One "gotcha" is that the regulation only requires the full TIN including the date code on one sidewall. The regulation does require a partial TIN which does not include the date code on the other sidewall. Typically the partial TIN is on the outer sidewall to improve the appearance. You might not be able to easily see the date code on tires on a vehicle. Some manufacturers do choose to put the full TIN on both sidewalls.

The other gray area is related to those "manufacturers" who use a process to overlay a white sidewall or special markings over an existing tire. While that process should not cover the full TIN it might if the tire gets put into their process the wrong way.