LESSON 1 OF 10

Reading the DOT Code

YOU WILL BE ABLE TO

Locate and interpret the four-digit DOT date code on a tire sidewall.
Determine the week and year of manufacture for tires produced since 2000.
Identify warranty limitations for Hankook ST tires based on manufacture date and ozone cracking.

TOOLS AT THE BAY

Inspection light — Locate the DOT Tire Identification Number, which may only be present on one sidewall.
Mirror — Read the DOT code on the inner sidewall if the outer sidewall does not contain the full date code.
Tire crayon — Mark the date of manufacture on the tire for quick reference during multi-unit inspections.

Since 2000 the last four digits of the DOT Tire Identification Number are week and year. Example: 0309 = 3rd week of 2009.

The full date code may be on only one sidewall.

Hankook ST warranty coverage ends 6 years from manufacture; ozone/weather cracking on tires over 4 years old isn't covered.

How It Works

Modern DOT Code Structure

Since 2000, the final four digits of the DOT Tire Identification Number represent the specific week and year of production. For example, a code of 0309 indicates the tire was manufactured during the 3rd week of 2009.

Sidewall Consistency

The full Tire Identification Number, including the date code, is not required to be on both sides of the tire. A technician may need to inspect both the inboard and outboard sidewalls to locate the complete date sequence.

Manufacturer Warranty Windows

Warranty periods are strictly tied to the manufacture date. For Hankook ST tires, coverage expires 6 years from the date of manufacture, regardless of the purchase date or tread depth.

Diagnostic Chart

Symptom	Check	Spec / Expected	Likely cause & fix
DOT date code is missing from the outboard sidewall.	Inspect the opposite (inboard) sidewall for the full Tire Identification Number.	Per the applicable manual	The full date code may be on only one sidewall. Basis: USTMA Tire Care & Safety Guide (2024)
Hankook ST tire has ozone/weather cracking.	Read the DOT code to determine the age of the tire.	Ozone/weather cracking on tires over 4 years old isn't covered.	The tire has exceeded the age threshold for weather-related warranty coverage. Basis: USTMA Tire Care & Safety Guide (2024)
Uncertainty regarding Hankook ST warranty eligibility.	Calculate the time elapsed between the DOT date code and the current date.	Warranty coverage ends 6 years from manufacture.	The tire may have exceeded the 6-year total warranty lifespan. Basis: USTMA Tire Care & Safety Guide (2024)

At the Bay: Diagnose the Case

CASE 1 / 3

DOT date code is missing from the outboard sidewall.

Test
Compare
Correct

Select the next check

Basis: USTMA Tire Care & Safety Guide (2024). A likely cause is a hypothesis; confirm it with the applicable service procedure before repair.

Common Bay Mistakes

✕ Assuming a tire is new because it has deep tread, without checking the DOT code.
✕ Looking only at the outboard sidewall and concluding the date code is missing.
✕ Misinterpreting the 0309 code as March 2009 instead of the 3rd week of 2009.
✕ Promising warranty coverage for weather cracking on a 5-year-old Hankook ST tire.
✕ Using the purchase date instead of the manufacture date to calculate Hankook warranty expiration.

Quick Check

Practice only — not scored.

The bay reports: DOT date code is missing from the outboard sidewall. Which check addresses this condition?

The bay reports: Hankook ST tire has ozone/weather cracking. Which check addresses this condition?

The bay reports: Uncertainty regarding Hankook ST warranty eligibility. Which check addresses this condition?

Source: USTMA Tire Care & Safety Guide (2024) — DOT Tire Identification

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