# DOT Numbers: 0 or O?

In DOT numbers how can I tell the difference between 0 (zero) and O (capital o)? Most fonts used on tire sidewalls make them difficult to tell apart, and I can't find any rules online saying that capital O's aren't used, so I'm left to guess on a case-by-case basis. I know the last four digits are numbers-only because they tell when the tire was manufactured, but on all tires I've seen any zeros in the last four digits are indistinguishable from the capital O in "DOT".

It's very important to keep accurate record of DOT numbers in my line of work (winter tire traction testing), but unfortunately I haven't been able to find anyone who can really help me with this issue.

Also sorry if this isn't the right forum for this question, it was the first forum I found where I thought people might know the answer.

The last four digits are the age information and are only numbers.

"I know the last four digits are numbers-only because they tell when the tire was manufactured, but on all tires I've seen any zeros in the last four digits are indistinguishable from the capital O in "DOT"

(I cannot digest that statement, if you know the last 4 are numbers only then you do not need to distinguish, you already know.)

The following is quote from Tirerack.com

The way to determine the age of a tire is easy once you know what to look for. Every tire has an identification number starting with "DOT", followed by a series of numbers and letters with the last four numbers identifying the tire's age. The last two are the production year, while the first two identify the week in which the tire was made. In the picture below, the sequence ends in "5107", which shows the tire was produced in the 51st week of 2007.

( despite my instance that i know everything, i do not in fact know everything. )