New vs Worn Circumference Calculator
Compare the approximate circumference of a tire when new and when worn. See the rolling distance lost per revolution and per mile.
Compare approximate circumference changes.
New vs Worn Circumference Calculator: Tire Size Inputs
Compare two tire sizes here. Use the formulas and reference tables below for this tool's specific calculation.
How New vs Worn Circumference Calculator Works?
The New vs Worn Circumference Calculator works by calculating the circumference at the new tread depth and at the worn tread depth and subtracting the 2 values. The tool uses 3 steps.
Enter size and new tread
Type the size and the new tread depth, for example 265/70 R17 with 15/32 in (11.9 mm).
Enter the worn tread
Type the worn depth, for example 2/32 in (1.6 mm).
Read the change
The calculator returns 2,522 mm new, 2,457 mm worn and a loss of 65 mm (2.56 in) per revolution, −2.57%.
New vs Worn Circumference Calculator Formula
The New vs Worn Circumference Calculator formula is ΔC = −2π × (TD_new − TD_worn).
C_new = π × OD_newC_worn = π × (OD_new − 2 × ΔTD)ΔC = −2π × ΔTD- ΔTD
- Tread worn away (mm)
- C_new, C_worn
- Circumference new and worn (mm)
Worked example
A 225/45 R17 tire worn from 10/32 in to 2/32 in loses 6.35 mm of tread. Circumference drops by 2π × 6.35 = 39.9 mm (1.57 in), from 1,993 mm to 1,953 mm, or −2.00%.
New vs Worn Circumference Calculator Conversion Table
The New vs Worn Circumference Calculator conversion table compares new and fully worn circumference for 5 sizes.
| Size | Tread range | New | Worn | Change |
|---|---|---|---|---|
| 205/55 R16 | 10/32 → 2/32 in | 1,985 mm | 1,945 mm | -40 mm (-2.01%) |
| 225/45 R17 | 10/32 → 2/32 in | 1,993 mm | 1,953 mm | -40 mm (-2.00%) |
| 235/45 R18 | 10/32 → 2/32 in | 2,101 mm | 2,061 mm | -40 mm (-1.90%) |
| 265/70 R17 | 15/32 → 2/32 in | 2,522 mm | 2,457 mm | -65 mm (-2.57%) |
| 275/55 R20 | 15/32 → 2/32 in | 2,546 mm | 2,481 mm | -65 mm (-2.55%) |
What is New vs Worn Circumference Calculator?
A New vs Worn Circumference Calculator is a tool that shows how much rolling distance a tire loses per turn between new and worn tread. A worn tire turns more times per mile than a new tire of the same size.
The circumference change from wear is 1.5% to 2.6%, which is close to the 3% guideline used for size changes. A new tire next to a worn tire on an AWD car creates the same mismatch as a different size.
The calculation uses nominal diameter and the given tread depths.
What are the uses of New vs Worn Circumference Calculator?
There are 4 main uses of the New vs Worn Circumference Calculator, including AWD replacements and odometer accuracy.
AWD replacements
Measure the mismatch of one new tire against 3 worn tires.
Odometer accuracy
Track odometer change across a tire's life.
Data logging
Update rolling circumference in loggers as tires wear.
Fleet calibration
Pick a mid-life circumference for telematics.
Related Core Tire Dimensions Tools
View All 134 Subtools →Compare two tire sizes.
Compare several sizes together.
Estimate nominal overall diameter.
Calculate absolute and percentage differences.
Estimate nominal circumference.
Compare estimated rolling distances.