Final answer:
The last four digits of the DOT number on tires are critical for warranty purposes as they indicate the tire's manufacturing date, which is required to assess warranty eligibility.
Step-by-step explanation:
For warranty purposes, the most important part of the DOT number is the last four digits. The DOT number on tires indicates compliance with the U.S. Department of Transportation tire safety standards, and the last four digits specifically indicate the week and year of manufacture. This is important for warranty purposes because it provides a time stamp for the tire's age, which can be crucial when determining eligibility for warranty claims in case of defects or premature wear.