Tire Size Calculator
Calculate tire dimensions and compare different tire sizes
Tire Size Calculator
Table of Contents
How to Read Tire Size
Understanding tire size markings is essential for proper tire selection. The standard format is:
Width/Aspect Ratio R Rim Diameter
Example: 225/60R16
- Width (225): Tire width in millimeters from sidewall to sidewall
- Aspect Ratio (60): Sidewall height as a percentage of tire width
- R: Indicates radial tire construction
- Rim Diameter (16): Wheel diameter in inches
Tire Calculations Explained
Our calculator performs several key calculations to provide comprehensive tire information:
- Sidewall Height: Calculated as (tire width × aspect ratio) ÷ 100
- Overall Tire Height: (2 × sidewall height) + rim diameter
- Circumference: π × overall tire height
- Revolutions per Mile: 63,360 inches ÷ tire circumference
- Speedometer Error: Based on circumference differences between tires
Speedometer Error Impact
When you change tire sizes, your speedometer accuracy can be affected because it's calibrated for the original tire size:
- Larger tires: Make your speedometer read slower than actual speed
- Smaller tires: Make your speedometer read faster than actual speed
- Odometer accuracy: Also affected by tire size changes
- Fuel economy: Can be impacted by speedometer errors affecting driving patterns
Use our calculator to determine the exact speedometer error when considering different tire sizes.
Practical Applications
This tire size calculator is useful for various automotive applications:
- Selecting replacement tires with different specifications
- Performance tuning and wheel upgrades
- Understanding the impact of tire changes on vehicle dynamics
- Fleet management and tire standardization
- Calculating accurate mileage and fuel consumption
- Ensuring compliance with vehicle manufacturer recommendations
- Comparing tire options for seasonal changes
Frequently Asked Questions
How do I read tire size markings?
Tire size is typically marked as three numbers separated by slashes and letters, such as 225/60R16. The first number (225) is the width in millimeters, the second (60) is the aspect ratio (sidewall height as percentage of width), and the third (16) is the rim diameter in inches.
What happens if I use a different tire size than recommended?
Using different tire sizes can affect speedometer accuracy, fuel economy, handling, and safety. Larger tires may improve handling but can reduce acceleration and fuel economy. Smaller tires may improve acceleration but could affect stability at high speeds.
How much speedometer error is acceptable?
Generally, a speedometer error of ±3% is considered acceptable. Errors beyond this range may affect vehicle performance, fuel economy, and could potentially cause legal issues if your speedometer reads significantly slower than your actual speed.
Can I mix different tire sizes on my vehicle?
It's generally not recommended to mix tire sizes unless specified by the manufacturer. Different tire sizes can cause uneven wear, affect traction control systems, and potentially damage the drivetrain in all-wheel-drive vehicles.