Tire Age Comparator
Compare DOT manufacture dates across a full set of tires including the spare. Find the oldest tire and the age gap across the set.
Compare manufacture dates across a set.
Tire Age Comparator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Tire Age Comparator Works?
The Tire Age Comparator works by decoding the DOT date code of every tire in a set and sorting the tires from newest to oldest. The tool uses 3 steps.
Enter each code
Type the 4-digit DOT date code for every position, including the spare.
Decode the dates
The comparator converts each code into a manufacture date and an age.
Read the spread
The comparator shows the oldest tire, the age gap from the newest and any tire past a chosen age limit.
Tire Age Comparator Formula
The Tire Age Comparator formula is Age gap = Age_oldest − Age_newest across the set.
Age_i = Today − D_iAge_max = max(Age_i)G = Age_max − Age_min- D_i
- Manufacture date of tire i
- G
- Age spread across the set
Worked example
A set with codes 1524, 1524, 3821 and 0123 plus a 2218 spare has an oldest road tire at 5.2 years and a spare at 8.4 years. The road tire age gap is 2.6 years.
Tire Age Comparator Conversion Table
The Tire Age Comparator conversion table shows a sample set of 5 tires with age and the gap from the newest tire.
| Position | DOT code | Manufactured | Age | Note |
|---|---|---|---|---|
| Left front | 1524 | Week 15, 2024 | 2.6 years | — |
| Right front | 1524 | Week 15, 2024 | 2.6 years | — |
| Left rear | 3821 | Week 38, 2021 | 5.2 years | Oldest, +2.6 years |
| Right rear | 0123 | Week 1, 2023 | 3.9 years | +1.3 years |
| Spare | 2218 | Week 22, 2018 | 8.4 years | Replace soon |
What is Tire Age Comparator?
A Tire Age Comparator is a tool that compares the manufacture dates of every tire on a vehicle. Sets often hold tires of different ages after single-tire replacements.
Older tires harden and lose grip, especially in the wet and cold. A mixed-age set has uneven grip between positions.
The spare is often the oldest tire on the vehicle and the most overlooked.
What are the uses of Tire Age Comparator?
There are 4 main uses of the Tire Age Comparator, including used car checks and mixed-set planning.
Used car checks
Find the oldest tire on a car before purchase.
Mixed-set planning
Place the newest tires on the rear axle for stability.
Spare tracking
Catch an aged spare before it is needed.
Fleet records
Track age across many vehicles.
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