Fitment Industries Tire Size Comparison Tool

Tire Size Calculator

Decode Your Tire Specs

Tire sizes look complicated until you know what the numbers mean.

Take a common size like 265/70R17.

Each part tells you something important about the tire:

• 265: Tire width in millimeters.
• 70: Aspect ratio — the sidewall height as a percentage of the tire width.
• 17: Wheel diameter (in inches) the tire fits.

Changing any of these numbers changes the tire’s overall diameter, which can affect:

• Speedometer accuracy
• Gear ratios
• Fender clearance
• Ride height

Going up in tire size is one of the most common upgrades for trucks and SUVs, but jumping sizes without understanding the difference can lead to rubbing or drivetrain stress.

This calculator breaks down the exact dimensions of your tire and compares them against new sizes so you know exactly what you're running.

It’s also helpful when you're trying to:

• Match metric and inch-based tire sizes
• Maintain a specific overall diameter
• Plan tire upgrades alongside new wheels

Check your tire dimensions and make sure your next size upgrade fits your build.