Usable Tread Percentage Calculator
Calculate usable tread left as a percentage between new depth and a chosen replacement threshold: 2/32, 4/32 or 5/32 inch.
Compare tread with a selected replacement threshold.
Usable Tread Percentage Calculator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How Usable Tread Percentage Calculator Works?
The Usable Tread Percentage Calculator works by dividing the tread above the replacement threshold by the tread a new tire has above the same threshold. The tool uses 3 steps.
Enter new tread depth
Type the new depth, for example 10/32 in (7.9 mm).
Pick a threshold
Choose 2/32 in (legal), 4/32 in (wet) or 5/32 in (snow).
Enter the current reading
Type the reading, for example 6/32 in. The calculator returns 50% usable to 2/32 and 33% usable to 4/32.
Usable Tread Percentage Calculator Formula
The Usable Tread Percentage Calculator formula is Usable % = (TD_now − TD_min) ÷ (TD_new − TD_min) × 100.
U% = (TD_now − TD_min) ÷ (TD_new − TD_min) × 100U_mm = TD_now − TD_min- TD_now
- Current tread depth
- TD_min
- Replacement threshold
- TD_new
- New tread depth
Worked example
A tire with 7/32 in left, a new depth of 10/32 in and a 4/32 in threshold has (7 − 4) ÷ (10 − 4) = 50% usable tread, or 3/32 in (2.4 mm) before replacement.
Usable Tread Percentage Calculator Conversion Table
The Usable Tread Percentage Calculator conversion table lists usable tread at 9 readings for 3 replacement thresholds.
| Current reading | To 2/32 in | To 4/32 in | To 5/32 in |
|---|---|---|---|
| 10/32 in (7.9 mm) | 100% | 100% | 100% |
| 9/32 in (7.1 mm) | 88% | 83% | 80% |
| 8/32 in (6.3 mm) | 75% | 67% | 60% |
| 7/32 in (5.6 mm) | 62% | 50% | 40% |
| 6/32 in (4.8 mm) | 50% | 33% | 20% |
| 5/32 in (4.0 mm) | 38% | 17% | 0% |
| 4/32 in (3.2 mm) | 25% | 0% | 0% |
| 3/32 in (2.4 mm) | 12% | 0% | 0% |
| 2/32 in (1.6 mm) | 0% | 0% | 0% |
What is Usable Tread Percentage Calculator?
A Usable Tread Percentage Calculator is a tool that shows how much of a tire's useful tread remains before a chosen replacement point. Tread below the threshold does not count, so a tire at 4/32 in has 0% usable tread on a 4/32 in threshold.
Percent of new depth overstates life left. A 10/32 in tire at 5/32 in has 50% of its new depth, and only 37.5% of its usable tread to 2/32 in.
Used tire sellers and lease returns often state tread as a percentage, and the calculator puts those claims on a common footing.
What are the uses of Usable Tread Percentage Calculator?
There are 4 main uses of the Usable Tread Percentage Calculator, including used tire pricing and lease return checks.
Used tire pricing
Price used tires by usable tread left.
Lease return checks
Compare tread with the lease's minimum.
Winter readiness
Check usable tread against a snow threshold before winter.
Budget timing
Plan the next tire purchase from tread left.
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