Tire Size Calculator
Compare tire sizes and calculate dimensions with precision and ease.
Current Tire Size
New Tire Size
Tire Comparison Results
Current Tire
Tire Size:
Sidewall Height:
Overall Diameter:
Circumference:
Revs per Mile:
New Tire
Tire Size:
Sidewall Height:
Overall Diameter:
Circumference:
Revs per Mile:
Difference
Diameter Difference:
Circumference Diff:
Speedo Error at 60mph:
Ground Clearance:
Width Difference:
About Our Tire Size Calculator
Our Tire Size Calculator is a powerful, user-friendly tool designed to help vehicle owners accurately compare different tire sizes and understand how changes in tire dimensions affect vehicle performance, appearance, and speedometer accuracy.
Why Compare Tire Sizes?
Changing your vehicle's tire size can have significant impacts on performance, handling, fuel efficiency, and even your speedometer's accuracy. Many enthusiasts upgrade tire sizes for aesthetic reasons or improved performance, but it's crucial to understand the full implications of these changes. Our calculator helps you make informed decisions before purchasing new tires.
Key Features:
- Precise calculation of sidewall height based on tire dimensions
- Overall diameter and circumference comparisons
- Speedometer error calculation when changing tire sizes
- Ground clearance and width difference analysis
- Revolutions per mile calculations for each tire size
- Easy-to-understand visual comparisons with instant results
How to Use:
- Enter your current tire's width in millimeters (the first number in your tire size)
- Input the aspect ratio (the middle number, representing the percentage of width to sidewall height)
- Enter the rim diameter in inches (the last number in your tire size)
- Repeat steps 1-3 for the new tire size you're considering
- Click "Compare Tire Sizes" to see detailed comparison results
Understanding Your Results:
Sidewall Height: The height of the tire's sidewall, calculated as a percentage of the tire width.
Overall Diameter: The total diameter of the tire including the rim, which affects ground clearance and speedometer accuracy.
Circumference: The distance around the tire, which directly impacts speedometer readings.
Revs per Mile: The number of complete rotations the tire makes over one mile, which affects engine RPM at cruising speeds.
Speedometer Error: The percentage difference between what your speedometer reads and your actual speed with the new tire size.
Ground Clearance: The change in ride height that results from the diameter difference between tire sizes.
Making Smart Tire Decisions
A significant change in tire size can affect more than just your vehicle's appearance. It can impact handling, braking performance, transmission behavior, and even void your vehicle warranty if the change is too extreme. Generally, staying within 3% of the original tire's overall diameter is recommended for most vehicles to minimize negative effects.
Beyond Basic Calculations
While our calculator provides essential metrics for comparing tire sizes, remember that other factors should also be considered when upgrading tires, including load rating, speed rating, tread pattern, and tire compound. These factors affect safety, comfort, and performance. Additionally, ensure any new tire size will physically fit your vehicle without rubbing against fenders or suspension components.
Perfect for car enthusiasts, tire shoppers, and vehicle owners looking to understand the implications of tire size changes. Start comparing your tire options today!
Frequently Asked Questions
How do I read my tire size?
Tire sizes follow a standard format like 225/50R17. The first number (225) is the width in millimeters. The second number (50) is the aspect ratio - the sidewall height as a percentage of the width. The "R" means radial construction, and the final number (17) is the rim diameter in inches.
How does tire size affect my speedometer?
Your vehicle's speedometer is calibrated based on the original tire's circumference. If you install larger tires, your actual speed will be faster than what your speedometer shows, while smaller tires will make your actual speed slower than indicated. Our calculator shows this difference as "Speedometer Error."
What is a safe amount of tire size change?
Most experts recommend staying within 3% of your original tire's overall diameter. Larger changes may require speedometer recalibration and could affect vehicle handling, braking, and electronic safety systems. Always consult your vehicle manufacturer's recommendations before making significant changes.
Will changing tire size affect my fuel economy?
Yes, tire size changes can impact fuel economy. Larger, heavier tires require more energy to rotate and may increase rolling resistance. Wider tires typically create more aerodynamic drag. However, taller tires with the same width might slightly improve highway fuel economy by effectively creating a higher gear ratio.
Can I put different sized tires on the front and rear?
Some high-performance vehicles come from the factory with a staggered setup (different sizes front and rear). For most vehicles, however, using different sizes can affect handling balance and may cause issues with traction control and ABS systems. Always consult with a professional before implementing a staggered setup on a vehicle not designed for it.