Tire Size Comparison

The Tire Size Comparison substitutes your inputs (Width 1 (mm), Aspect ratio 1 (%), Rim diameter 1 (in), Width 2 (mm), Aspect ratio 2 (%), Rim diameter 2 (in)) into the standard expression: Diameter 1 (mm) = Rim diameter 1 (in) × 25.4 + 2 × Width 1 (mm) × Aspect ratio 1 (%) ÷ 100; Diameter 2 (mm) = Rim diameter 2 (in) × 25.4 + 2 × Width 2 (mm) × Aspect ratio 2 (%) ÷ 100; Diameter difference = (Rim diameter 2 (in) × 25.4 + 2 × Width 2 (mm) × Aspect ratio 2 (%) ÷ 100 − (Rim diameter 1 (in) × 25.4 + 2 × Width 1 (mm) × Aspect ratio 1 (%) ÷ 100)) ÷ (Rim diameter 1 (in) × 25.4 + 2 × Width 1 (mm) × Aspect ratio 1 (%) ÷ 100) × 100. Every variable is read straight from the fields on this page, and the result is computed the moment you enter the values.

1. 1

   Step 1

   Specify the vehicle specifications.

2. 2

   Step 2

   Click the "Calculate" button to see the result instantly.

3. 3

   Step 3

   Review the result and details below before relying on it.

4. 4

   Step 4

   Review the breakdown: the tire size comparison shows each of your inputs substituted into the page's standard expression, so every variable stays traceable.

5. 5

   Step 5

   Compare scenarios by varying a single value per run in the tire size comparison — that isolates which of the formula's inputs actually drives the result.

• 1

  The Tire Size Comparison needs every variable in consistent units — Width 1 (mm) — before the standard formula returns a valid result, so check each field's unit before entering values copied from elsewhere.

• 2

  For repeated what-if work on Tire Size Comparison, change one input at a time and note the effect; that isolates which variable actually drives the result instead of moving several values at once and losing the attribution.

• 3

  Enter values in the units the Tire Size Comparison fields expect — Width 1 (mm) and the rest; mismatched units are the most common way a correct formula yields a wrong number no calculator can detect.

• Zero and negatives can sit outside the formula's domain: zero aspect ratio 1 (%) may make the Tire Size Comparison undefined, and a negative width 1 (mm) still returns a number. Check each input is inside the range the quantity allows.

• Percentage conventions differ by field: some Tire Size Comparison inputs expect aspect ratio 1 (%) as a whole number (5 for 5%), others as a decimal (0.05). The two forms are off by ×100 — match the field's label or example.