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Snow Chain Size Calculator

Use our Snow Chain Size Calculator to find the perfect tire chain size in seconds. Easy, accurate, and beginner-friendly for winter driving.

Format: Width/AspectRatio R RimDiameter
mm
%
in

Winter roads can be tricky. Snow and ice make driving unsafe if your tires slip. That’s where snow chains come in. But many drivers ask the same thing: How do I know what size snow chain I need?

That’s why we built the Snow Chain Size Calculator. With it, you’ll get the right chain size for your tires in seconds. No guesswork. No confusion. Just clear results.

How the Calculator Works

The calculator uses the standard tire size formula. Every tire has a code, like 225/55R17. That code gives us three numbers:

  • Tire width in millimeters
  • Aspect ratio in percent
  • Rim diameter in inches

From these numbers, we find the chain length by first working out the tire’s circumference.

The Formula

Sidewall height (mm):

sidewall = width × (aspect ratio ÷ 100)

Rim diameter (mm):

rim_diameter = rim_inches × 25.4

Overall diameter (mm):

overall = rim_diameter + (2 × sidewall)

Circumference (mm):

circumference = π × overall

That final circumference gives the chain length you’ll need.

Example

Take a 225/55R17 tire.

  • Sidewall height = 225 × 0.55 = 123.8 mm
  • Rim diameter = 17 × 25.4 = 431.8 mm
  • Overall diameter = 431.8 + (2 × 123.8) = 679.4 mm
  • Circumference = 3.1416 × 679.4 = 2134.6 mm

So, the right snow chain size is about 2135 mm (84 inches).

How to Use the Calculator

Using the tool is simple.

Enter your tire code (like 205/55R16). The calculator then does the math for you. It shows the sidewall height, rim size in mm, total diameter, and final chain length.

It’s as easy as entering numbers and clicking a button.

Do You Need Two or Four Chains?

This is a common question. Most drivers only need two chains for the drive wheels. If you have a front-wheel-drive car, put them on the front tires. If you have rear-wheel drive, they go on the back tires.

But for extra grip and safety, especially in heavy snow, you can use four chains. That means all wheels have chains.

What If Chains Are Too Big?

Chains that are too big can slip. That’s dangerous. They may hit the car body or damage brakes. Always follow the chain maker’s fit chart to match your tire code. The calculator gives you the math, and the chart confirms the fit.

9mm vs 12mm Snow Chains

You’ll also see chains labeled by thickness, like 9mm or 12mm.

  • 9mm chains are slimmer. They work better on small cars or when space around the wheel is tight.
  • 12mm chains are stronger. They give more bite on heavy snow but need more clearance.

Pick the one your car allows. Check your manual if you’re not sure.

Final Verdict

Snow chains aren’t just winter gear. They’re peace of mind. The wrong size can cause accidents, but the right size makes your car safe on icy roads.

The Snow Chain Size Calculator takes away the hard part. It uses your tire code and gives you the exact numbers. Simple, fast, and reliable.

FAQs

How do I know what size snow chain I need?

Enter your tire code into the calculator. It gives you the correct chain size in mm and inches.

Do I need 2 or 4 chains for snow?

Two are enough for most cars. Four give extra safety in deep snow.

What if my snow chains are too big?

They may slip and damage your car. Always use the right size.

What’s the difference between 9mm and 12mm snow chains?

9mm are slimmer and fit tight spaces. 12mm are stronger but need more clearance.