Tire Size Calculator — Compare Tire Sizes, Calculate Dimensions

Tire Size Calculator

Calculate tire dimensions, compare different tire sizes, and understand how tire changes affect speedometer accuracy, clearance, and vehicle performance.

Step 1: Original Tire Size

Understanding Tire Size Notation

Example: 225/45R17 means 225mm width, 45% aspect ratio (sidewall height is 45% of width), and 17-inch wheel diameter. The “R” stands for radial construction.

Step 2: New Tire Size

Tire Size Impact

Changing tire size affects speedometer accuracy, ground clearance, handling, and fuel efficiency. Larger wheels may improve looks but can reduce ride comfort.

Tire Size Comparison Results

Summary
Detailed Comparison
Performance Impact

Size Comparison

225/45R17235/40R18
New tire is 1.8% larger in diameter
Overall Diameter
25.0″
+0.4″ (+1.8%)
Sidewall Height
4.0″
-0.2″ (-5.0%)
Circumference
78.4″
+1.4″ (+1.8%)
Revolutions per Mile
808
-15 (-1.8%)
Speedometer Reading
60 mph
Actual: 61.1 mph
Clearance Change
+0.2″
Ground clearance increased

Detailed Tire Size Comparison

Dimension Original Tire New Tire Difference Impact

Performance Impact Analysis

How Tire Size Affects Your Vehicle

Key Considerations When Changing Tire Size

Larger diameter tires can improve ground clearance and high-speed stability but may reduce acceleration and fuel efficiency. Smaller sidewalls provide better handling but reduce ride comfort. Always ensure new tires fit within your wheel wells and don’t rub against suspension components.

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