Tire Size Calculator
Original Tire Size
New Tire Size
Calculation Results
Original Tire
Overall Diameter
-
Sidewall Height
-
Circumference
-
Revolutions per Mile
-
New Tire
Overall Diameter
-
Sidewall Height
-
Circumference
-
Revolutions per Mile
-
17"
Original Tire
18"
New Tire
Tire Comparison
| Parameter | Original Tire | New Tire | Difference | Percentage |
|---|---|---|---|---|
| Overall Diameter (inches) | - | - | - | - |
| Sidewall Height (inches) | - | - | - | - |
| Circumference (inches) | - | - | - | - |
| Revolutions per Mile | - | - | - | - |
| Speedometer Reading at 60 mph | 60 mph | - | - | - |
How to Use the Tire Size Calculator
Understanding Tire Sizes
Tire sizes are typically represented as three numbers, such as 225/45R17. Let's break down what each number means:
- 225 - The tire width in millimeters (the distance from sidewall to sidewall)
- 45 - The aspect ratio (the sidewall height as a percentage of the tire width)
- 17 - The rim diameter in inches (the diameter of the wheel the tire fits)
Step-by-Step Guide to Using the Calculator
- Enter your current tire size in the "Original Tire Size" section. Input the width, aspect ratio, and rim diameter.
- Enter your proposed new tire size in the "New Tire Size" section.
- Click "Calculate" to see the detailed comparison between your current and proposed tire sizes.
- Review the results to understand how the new tire size will affect your vehicle's performance, speedometer accuracy, and overall driving experience.
- Use the comparison table to see the exact differences between the two tire sizes in both absolute and percentage terms.
Why Tire Size Matters
Changing your tire size can have several important effects on your vehicle:
- Speedometer Accuracy - Larger tires cover more ground per revolution, which can cause your speedometer to read slower than your actual speed.
- Acceleration and Braking - Larger, heavier tires can reduce acceleration and increase braking distances.
- Fuel Economy - Heavier tires and altered gearing can impact fuel efficiency.
- Ride Comfort - Tires with taller sidewalls generally provide a smoother ride by absorbing more road imperfections.
- Clearance - Ensure your new tires won't rub against wheel wells or suspension components.
Tips for Choosing the Right Tire Size
- Always consult your vehicle's manual for recommended tire sizes.
- Stay within 3% of your original tire's overall diameter to maintain accurate speedometer readings.
- Consider your driving conditions - taller sidewalls for rough roads, lower profiles for performance driving.
- Check local regulations as some areas have restrictions on tire size modifications.
- Consult with a professional if you're unsure about compatibility.
Frequently Asked Questions
Our calculator uses standard tire industry formulas to provide highly accurate results. However, actual tire dimensions can vary slightly between manufacturers and models due to tread design and construction differences.
Yes, this calculator works for any vehicle that uses standard tire sizing, including cars, trucks, SUVs, and motorcycles. Simply input your current and proposed tire sizes to see the comparison.
Generally, it's recommended to stay within 3% of your original tire's overall diameter. Beyond this, you may experience significant speedometer inaccuracies, potential clearance issues, and possible strain on your vehicle's drivetrain.