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Everyday LifeGenerated accuracy model review: 2026-05-06
Tire Size Calculator accuracy and testing
This page documents how Calwarden builds trust for this calculator: source notes, regression-style default tests, limitations, assumptions, unit handling, rounding, and visible change history.
Formula source
- 1. **Sidewall Height (mm)** = Width × (Ratio/100). 2. **Sidewall (in)** = Sidewall (mm) / 25.4. 3. **Total Diameter** = Rim + (2 × Sidewall).
Test cases
Default input regression check
Generated from the checked-in default inputs and calculate function.
Inputs
- Width (mm): 205
- Aspect Ratio: 55
- Rim Diameter: 16 in
Expected outputs
- Total Diameter: 24.88 in
- Sidewall Height: 4.44 in
- Circumference: 78.16 in
Known limitations
- This page documents the checked-in calculator logic and does not certify results for every real-world edge case.
- Use the result as a planning estimate unless the calculator page states a stricter purpose.
Assumptions
- The tire size follows the standard metric format width/aspect-rim.
- The result is approximate and should be checked against the vehicle placard.
- Clearance, suspension, and load ratings are not modeled here.
Unit handling
- Width (mm) accepts numeric values.
- Aspect Ratio accepts numeric values.
- Rim Diameter accepts values in in.
- Total Diameter is displayed in in.
- Sidewall Height is displayed in in.
- Circumference is displayed in in.
Rounding rules
- Number displays use up to 2 decimal places in the calculator UI.
Version history
1.0.0 - 2026-05-06
Generated accuracy and testing page from the current tire-size-calculator calculator definition.
Change log
2026-05-06
Published default regression test documentation and metadata fallbacks for Tire Size Calculator.
Calculator transparency
Accuracy pages are generated from checked-in calculator definitions and can be upgraded with curated review metadata over time.