How to Find Your Tyre Size — A Simple Guide

Need a new tyre but not sure what size you need? You're not alone. Tyre sizes look like a secret code — something like 205/55R16 91V — but once you know how to read them, it's surprisingly simple. Here's everything you need to know to find your tyre size, whether you're standing next to your car or sitting on the sofa.

Where to Look: The Tyre Sidewall

The easiest place to find your tyre size is right on the tyre itself. Crouch down next to your wheel and look at the sidewall — the flat rubber surface between the tread and the rim. You'll see a sequence of numbers and letters printed in raised text. It's usually the largest marking on the sidewall, often starting with a three-digit number like 195, 205, or 225.

The full code will look something like this: 205/55R16 91V. That's the one you need. Write it down or take a photo with your phone. If the tyre is dirty, wipe it with a cloth — the markings can be hard to read through road grime.

Decoding the Numbers: What 205/55R16 Means

Let's break down that code piece by piece:

• 205 — The tyre width in millimetres, measured from sidewall to sidewall. This tyre is 205mm wide.
• 55 — The aspect ratio. This is the height of the sidewall as a percentage of the width. A 55 profile means the sidewall height is 55% of 205mm (about 113mm). Lower numbers mean a lower-profile, sportier tyre.
• R — Stands for Radial construction. Almost all modern car tyres are radial. You might occasionally see "D" for diagonal (bias-ply) on older or specialist vehicles.
• 16 — The wheel diameter in inches. This tyre fits a 16-inch wheel rim.

So 205/55R16 means: a 205mm-wide radial tyre with a 55% profile, designed to fit a 16-inch wheel. Simple once you know the formula.

Load Index and Speed Rating

After the size code, you'll usually see two more characters — for example, 91V. The number (91) is the load index — a code that tells you the maximum weight the tyre can carry. 91 means 615kg per tyre. The letter (V) is the speed rating — the maximum speed the tyre is designed for. V means up to 149mph. Common ratings include T (118mph), H (130mph), V (149mph), and W (168mph).

You should always replace a tyre with one that meets or exceeds the load index and speed rating specified for your vehicle. Your fitter will make sure of this, but it's good to know what those letters mean.

Other Places to Find Your Tyre Size

Can't get to the tyre? No problem. There are several other places your tyre size is recorded:

• Driver's door jamb — Open the driver's door and look at the sticker on the door frame or B-pillar. It lists the recommended tyre sizes and pressures for your vehicle.
• Owner's manual — The tyre specifications section will list all approved sizes for your car.
• Fuel filler cap — Some manufacturers print tyre pressure and size info inside the fuel flap.
• Online registration lookup — Many tyre retailer websites let you enter your number plate and will show the correct tyre size for your vehicle.

What If You're Still Not Sure?

Don't worry. If you can't find your tyre size or you're unsure you've read it correctly, just call us. Our mobile fitters carry a wide range of sizes in the van — over 100 different tyre sizes are stocked as standard. When the fitter arrives, they can identify the correct size directly from your existing tyre and fit the right replacement on the spot. You don't need to be a tyre expert — that's our job.

Why Getting the Right Size Matters

Fitting the wrong tyre size isn't just a bad idea — it can be dangerous. An incorrect size affects your speedometer accuracy, handling, braking distances, and could cause rubbing against the wheel arch or suspension components. It may also invalidate your insurance. Always match the size specified for your vehicle. If you're upgrading wheels or changing sizes intentionally, consult a professional first.