That's what I learned around 1984 from reading a book. 10 years before internet was a thing :) Have ignored all other numbers since then. Have not had any worse

That's what I learned around 1984 from reading a book. 10 years before internet was a thing :) Have ignored all other numbers since then. Have not had any worse problem than some clerk might have given me a strange look when I bought tires referring to ETRTO numbers.