Tire Equivalence Calculator - Compare Tire Sizes
Compare tire sizes and find equivalent alternatives
Table of Contents
How to Use
- Enter tire width in millimeters (e.g., 225)
- Enter aspect ratio (e.g., 45)
- Enter rim diameter in inches (e.g., 17)
- View tire specifications and equivalent sizes
- Compare alternative tire sizes within ±3% diameter
Understanding Tire Sizing
Tire sizes are written in a standard format like 225/45R17. The first number (225) is the tire width in millimeters, the second (45) is the aspect ratio (sidewall height as percentage of width), and the third (17) is the rim diameter in inches.
Why Find Equivalent Tires?
- Access to more tire brands and models
- Potentially better prices or availability
- Different performance characteristics
- Seasonal tire changes with different specs
- Replacement options when original size is discontinued
Why Diameter Matters
Overall tire diameter affects speedometer accuracy, vehicle clearance, and gear ratios. Most experts recommend staying within ±3% of the original diameter to avoid issues with speedometer readings, ABS systems, and vehicle handling.
Important Considerations
- Check vehicle manufacturer recommendations
- Ensure adequate clearance in wheel wells
- Verify load rating and speed rating match requirements
- Consider impact on fuel economy
- Professional installation and balancing recommended
Frequently Asked Questions
- What does the ±3% diameter difference mean?
- The ±3% refers to the difference in overall tire diameter. Staying within this range ensures your speedometer remains accurate and prevents issues with your vehicle's systems. A 3% difference typically means about 1-2 inches in diameter.
- Can I use any equivalent tire size shown?
- While these tires have similar diameters, always check your vehicle's manual for approved tire sizes. Consider factors like wheel well clearance, load rating, speed rating, and manufacturer recommendations before making changes.
- Will changing tire size affect my speedometer?
- Yes, tire diameter affects speedometer accuracy. Larger tires make the speedometer read slower than actual speed, while smaller tires make it read faster. Staying within ±3% keeps speedometer error minimal (typically under 2 mph at highway speeds).
- What is aspect ratio?
- Aspect ratio is the tire's sidewall height as a percentage of its width. For example, a 225/45 tire has a sidewall height that is 45% of 225mm (101.25mm). Lower aspect ratios mean shorter sidewalls and typically sportier handling.
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