Tire Size Calculator
Calculate tire dimensions, compare tire sizes, and find equivalent tire sizes. Get detailed tire specifications and measurements for your vehicle.
Tire Size Input
Compare with Another Tire
Tire Specifications
Detailed Measurements
Load & Speed Ratings
Tire Cross-Section
Plus Sizing Options
How to Use
Choose your input method: enter the complete tire size or individual components.
Enter your tire size in the standard format (e.g., 225/60R16) or input each component separately.
Optionally add load index and speed rating for complete tire specifications.
Compare with another tire size to see differences in diameter and speedometer impact.
Understanding Tire Sizes
Tire Size Format
Key Measurements
Width
The tire's width from sidewall to sidewall in millimeters when mounted and inflated.
Aspect Ratio
The sidewall height as a percentage of the tire width. Lower numbers mean shorter sidewalls.
Overall Diameter
The total height of the tire from ground to top, including the rim diameter and both sidewalls.
Circumference
The distance around the tire's outer edge, which affects speedometer readings and fuel economy.
Construction Types
R - Radial
Most common type. Cord plies run perpendicular to the direction of travel. Better fuel economy and longer tread life.
D - Diagonal/Bias
Older construction with cord plies at angles. Stronger sidewalls but less fuel efficient.
B - Belted Bias
Combination of bias and radial features. Rarely used in modern passenger vehicles.
Applications
Vehicle Maintenance
- • Tire replacement planning
- • Size verification
- • Load capacity checking
- • Speed rating confirmation
- • Maintenance scheduling
Performance Upgrades
- • Plus sizing calculations
- • Wheel and tire packages
- • Performance tire selection
- • Handling improvements
- • Aesthetic modifications
Professional Use
- • Tire shop operations
- • Fleet management
- • Vehicle specifications
- • Insurance assessments
- • Technical documentation
Example Calculations
Standard Passenger Car
Width: 225mm (8.9")
Sidewall Height: 135mm (5.3")
Overall Diameter: 676mm (26.6")
Circumference: 2,124mm (83.6")
Plus Size Upgrade
Plus 1: 225/55R17 (679mm diameter)
Plus 2: 225/50R18 (682mm diameter)
Difference: Less than 1% change in diameter
Result: Minimal speedometer error
Frequently Asked Questions
Can I use a different tire size than what's recommended?
You can use different sizes, but stay within 3% of the original overall diameter to avoid speedometer errors and potential safety issues. Always check load capacity and speed ratings.
What is plus sizing?
Plus sizing involves using a larger rim diameter with a lower profile tire to maintain the same overall diameter. This can improve handling and appearance while preserving speedometer accuracy.
How does tire size affect fuel economy?
Larger, wider tires typically reduce fuel economy due to increased rolling resistance and weight. Lower profile tires may also have higher rolling resistance than taller sidewall tires.
What happens if my speedometer is off?
If your tire diameter is larger than original, your speedometer will read slower than actual speed. If smaller, it will read faster. This also affects odometer readings and can impact warranty coverage.
Related Calculators
Speed Calculator
Calculate actual speed with different tire sizes
Fuel Cost Calculator
Calculate fuel costs and efficiency impacts
Conversion Calculator
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Percentage Calculator
Calculate percentage differences in tire sizes
Auto Loan Calculator
Calculate financing for tire and wheel upgrades
Circle Calculator
Calculate circumference and area for tire geometry