Calculate tire dimensions, compare tire sizes, and determine wheel compatibility. Convert tire codes to actual measurements with detailed analysis and visual representations.
This tire size calculator helps you understand tire dimensions, compare different tire sizes, and find compatible alternatives. Whether you're upgrading wheels or replacing tires, this tool provides accurate calculations for tire diameter, sidewall height, and overall dimensions.
Understanding tire sizes is crucial for vehicle safety, performance, and legal compliance. Use this calculator to ensure proper fitment and avoid issues with speedometer accuracy, handling, and vehicle clearance.
Where: Width = tire width in mm, Aspect Ratio = percentage of width
Where: Wheel Diameter = rim diameter in inches, converted to millimeters
Used for calculating speedometer differences and revolutions per mile
| Vehicle Type | Typical Width Range | Common Aspect Ratios | Wheel Sizes | Example Size |
|---|---|---|---|---|
| Compact Cars | 175-205mm | 60-70 | 15-17" | 195/65R15 |
| Mid-size Sedans | 205-225mm | 55-65 | 16-18" | 215/60R16 |
| Full-size Sedans | 225-245mm | 50-60 | 17-19" | 235/55R17 |
| Sports Cars | 225-285mm | 35-50 | 18-21" | 245/40R18 |
| SUVs/Crossovers | 225-275mm | 55-70 | 16-20" | 255/65R18 |
| Light Trucks | 235-285mm | 65-85 | 15-18" | 265/70R17 |
Speedometer Accuracy: Keep overall tire diameter within 3% of original to maintain accurate speedometer and odometer readings. Larger tires read slower than actual speed.
Load Rating: Ensure replacement tires have equal or higher load ratings than original equipment. Never downgrade load capacity for safety reasons.
Speed Rating: Match or exceed the original tire's speed rating. Higher ratings provide better high-speed stability and heat resistance.
Wheel Well Clearance: Check that larger tires don't rub against fenders, suspension components, or brake lines during full steering lock or suspension compression.
Wider Tires: Improve grip and cornering but may increase road noise, fuel consumption, and aquaplaning risk. Better for dry weather performance.
Lower Profile Tires: Enhance handling precision and appearance but reduce ride comfort and increase pothole damage risk. More expensive to replace.
Larger Wheel Diameter: Improves brake cooling and vehicle appearance but increases unsprung weight, replacement costs, and ride harshness.
Tire Pressure: Larger tires often require different pressures. Always follow manufacturer recommendations for optimal performance and safety.
| Speed Symbol | Maximum Speed | Application | Typical Use |
|---|---|---|---|
| Q | 99 mph (160 km/h) | Snow/Winter tires | Severe weather conditions |
| S | 112 mph (180 km/h) | Family sedans | Standard passenger cars |
| T | 118 mph (190 km/h) | Family sedans/vans | Standard touring applications |
| H | 130 mph (210 km/h) | Sport sedans/coupes | Sport touring applications |
| V | 149 mph (240 km/h) | Sports cars | High performance vehicles |
| W | 168 mph (270 km/h) | Exotic sports cars | Ultra-high performance |
| Y | 186 mph (300 km/h) | Supercars | Maximum performance rating |
Tire Age: Replace tires over 6 years old regardless of tread depth. Check DOT date codes during inspection to determine manufacturing date.
Tread Depth: Minimum legal tread depth is 2/32" in most areas, but 4/32" is recommended for safety, especially in wet conditions.
Rotation Patterns: Regular tire rotation extends tire life and ensures even wear. Follow vehicle-specific rotation patterns every 5,000-7,500 miles.
Alignment Impact: Proper wheel alignment prevents premature tire wear and improves fuel economy. Check alignment when installing new tires.