Tire Size Calculator for Classic Chevy and GM

Whether you're restoring a 1969 Camaro, upgrading your Chevelle's stance, or dialing in the perfect fitment for your El Camino, picking the right tire size is key. Use our calculator below to compare your current tire size to a new one and understand how the overall diameter and speedometer reading will change.

Where to Find Tire Size Information

You can find your current tire size printed on the sidewall of the tire. It will appear as a series of numbers like 225/60R15. Here's what those numbers mean:

• 225 - Tire width in millimeters
• 60 - Aspect ratio (sidewall height as a percentage of width)
• 15 - Wheel diameter in inches

For aftermarket tires you're considering, you'll typically see similar markings on product listings or spec sheets.

Here's a helpful diagram to show you what each of the numbers on a tire means.

Compare Tire Sizes

How to Use the Results

After calculating, you'll see the overall diameter of both your original and new tire setups. This information helps you:

• Choose proper fitment - Make sure your new tires won't rub on fenders or suspension components.
• Maintain speedometer accuracy - A significant change in diameter can cause your speedometer to read inaccurately.
• Match stance and style - Use the calculator to dial in the perfect muscle car look without compromising ride quality or geometry.

Ideally, you want the diameter difference to be within ±3% to avoid throwing off your speedometer or causing handling issues.