Verified for accuracy in automotive specifications and tire geometry calculations.
Use our professional tires size calculator to determine the exact dimensions of any tire. Simply enter the width, aspect ratio, and wheel diameter to calculate sidewall height, total diameter, circumference, and revolutions per mile instantly.
Tires Size Calculator
Tires Size Calculator Formula:
Total Diameter (D) = Wheel Diameter + 2 × (Width × Aspect Ratio / 100)
Circumference (C) = π × D
Revolutions/Mile = 63,360 / C
Source: Michelin – How to Read a Tire Sidewall
Variables:
- Section Width: The width of the tire in millimeters from sidewall to sidewall.
- Aspect Ratio: The height of the sidewall as a percentage of the section width.
- Wheel Diameter: The size of the wheel rim in inches that the tire is designed to fit.
Related Calculators:
What is tires size calculator?
A tires size calculator is a technical tool used by automotive enthusiasts and mechanics to understand the physical dimensions of a tire based on its standardized metric marking (e.g., 225/45R18). It translates metric width and percentage-based sidewall height into imperial inches, which is the standard for wheel sizing in many regions.
Understanding these measurements is crucial when upgrading wheels or tires to ensure the new setup doesn’t interfere with the vehicle’s suspension, wheel wells, or significantly alter the speedometer accuracy.
How to Calculate tires size calculator (Example):
- Identify Inputs: Tire size 225/45R18.
- Calculate Sidewall: 225mm × 0.45 = 101.25mm.
- Convert to Inches: 101.25mm / 25.4 = 3.99 inches.
- Total Diameter: 18″ + (2 × 3.99″) = 25.98 inches.
- Final Check: Use the diameter to find circumference and gearing changes.
Frequently Asked Questions (FAQ):
Does a larger tire affect my speedometer? Yes, a larger diameter tire covers more ground per revolution, making your speedometer read slower than your actual speed.
What does the ‘R’ stand for in a tire size? It stands for Radial, which refers to the internal construction of the tire’s plies.
How much diameter change is safe? Most experts recommend staying within ±3% of the original tire diameter to avoid clearance issues.
Why is the aspect ratio a percentage? It allows tire manufacturers to maintain proportional sizing across different widths while providing a clear indicator of performance characteristics.