Tire Size Calculator
Calculate tire dimensions, compare sizes, and find the perfect fit for your vehicle. Enter your tire specifications below to get instant results.
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Tire Visualization
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Size Comparison
Calculate a tire size and click “Add to Compare” to see side-by-side comparisons.
Tire Size Guide
Understanding Tire Size Notation
A tire size like “205/55R16” contains three key measurements:
- 205 – Tire width in millimeters
- 55 – Aspect ratio (sidewall height as percentage of width)
- 16 – Rim diameter in inches
- R – Radial construction type
What Gets Calculated
Our calculator provides these essential measurements:
- Sidewall Height – Distance from rim to tread
- Total Diameter – Overall tire height
- Circumference – Distance around the tire
- Revolutions/Mile – How many times tire rotates per mile
Why Size Matters
Correct tire sizing is crucial for:
- Speedometer accuracy
- Vehicle handling and stability
- Fuel efficiency
- Clearance and fitment
- Tire wear patterns
Common Tire Sizes Reference
| Tire Size | Width | Aspect Ratio | Rim | Diameter | Common Vehicle |
|---|---|---|---|---|---|
| 205/55R16 | 205mm | 55% | 16″ | 632mm | Compact cars |
| 225/65R17 | 225mm | 65% | 17″ | 724mm | SUVs, Crossovers |
| 265/70R17 | 265mm | 70% | 17″ | 803mm | Trucks |
| 235/45R18 | 235mm | 45% | 18″ | 672mm | Sports sedans |
| 275/40R19 | 275mm | 40% | 19″ | 702mm | Performance cars |
Frequently Asked Questions
You can change tire size, but the overall diameter should remain within 3% of the original size to maintain speedometer accuracy. Our calculator shows the diameter difference when comparing sizes. A larger tire will make your speedometer read slower than actual speed, while a smaller tire will make it read faster.
The aspect ratio is the height of the tire’s sidewall expressed as a percentage of its width. A lower aspect ratio (like 40) means a shorter sidewall, which provides sharper handling but a firmer ride. A higher aspect ratio (like 65) means a taller sidewall, offering more comfort but less responsive handling.
Generally, tire diameter should stay within 3% of the original equipment size. Width can typically vary by 20mm if wheel width allows. Always check your vehicle’s clearance, especially with wider tires. For best results, stick to manufacturer-recommended sizes or plus/minus one sizing with appropriate width adjustments.
Wider tires can provide better dry grip and cornering stability due to a larger contact patch. However, they may increase rolling resistance (reducing fuel economy), be more prone to hydroplaning in wet conditions, and can tramline on grooved roads. The ideal tire width depends on your driving conditions and priorities.
