Tire manufacture dating
The Rubber Manufacturers Association, a US based industry group that represents folks who manufacture things out of rubber (and tires are a major player in this group), has published a suggested list of codes: RMA Size Code Manual Please note: This manual also gets updated from time to time, so don't assume this version is 100% accurate either.Also do not assume that everyone uses this coding system.
It can be anything the tire manufacturer wants it to be - but there has to be a system that can be explained.While it may be true that all Michelin tires have an "X" in the type code, it is NOT true that Michelin is the only one who uses an "X" in the type code.Editorial Comment: One of the reasons I did this web site is because of things just like the photo to the right - Misinformation! Required sidewall data includes when and where a tire was manufactured. Department of Transportation rules require that tire manufacturers such as Yokohama provide specific information on their tires.The date of manufacture for a Yokohama tire is provided in an easy-to-decipher code.
Find the Department of Transportation number on the tire.
The first 2 or 3 digits are a code for the manufacturing plant.
Prior to April of 2015, all plant codes were 2 digits, but after April of 2015, a third digit was permissible, and 3 digits are required by April of 2025.
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This means there will be a period of time where there will be both 2 digit and 3 digit plant codes.