How Do I Know Which Tyres Will Fit My Car?
A 60-second guide to reading the size code on your tyre's sidewall.
Not sure what tyre size you need? Don't worry — it's easier than you think. Every tyre has a size code printed on the sidewall, and once you know where to look, you can find it in seconds.
How to read your tyre size
Walk round to the side of any tyre and you'll see a string of numbers and letters moulded into the rubber, something like:
255/35 R19
That single line tells you everything you need to order a replacement. Here's what each part means:
255 — Tyre Width
The width of the tyre measured in millimetres from sidewall to sidewall. A 255 tyre is 255 mm wide. Wider tyres generally give more grip, narrower tyres are lighter and use less fuel.
35 — Aspect Ratio
The height of the sidewall as a percentage of the width. A 35 here means the sidewall is 35% of 255 mm — about 89 mm tall. Lower numbers (low-profile) look sportier and handle more sharply; higher numbers give a softer ride and more sidewall protection against potholes.
R19 — Rim Diameter
The R means radial construction (almost every modern tyre is radial), and the 19 is the diameter of the wheel in inches the tyre is designed to fit. A 19" wheel needs an R19 tyre — an R18 won't go on, and an R20 won't fit either.
Where to find your tyre size
You've got three places to check, in order of how easy they are:
- The tyre sidewall itself. Look at any of your current tyres — the size will be moulded into the rubber, usually on the outer face.
- Inside the driver's door jamb. Most cars have a sticker showing the manufacturer's recommended tyre size and pressures.
- Your handbook. The "Wheels and Tyres" section will list every size approved for your car.
If the four tyres on your car aren't all the same size, that's fine on some performance vehicles — but check each one rather than assuming.
Other markings worth knowing
After the size you'll often see a couple of extra characters — for example 255/35 R19 96Y:
- Load index (96) — how much weight each tyre can carry. Always fit at least the load index your car manufacturer specifies.
- Speed rating (Y) — the maximum speed the tyre is rated for (Y is 186 mph). Don't fit a lower speed rating than the original.
Still not sure? Let us check for you
The easiest way to be 100% certain is to enter your registration. Pop it into our tyre-fitting page and we'll show you the exact sizes that fit your car — with live prices including fitting and balancing.
Or call our Hull workshop on 01482 328800 and one of the team will read it off for you. We've been fitting tyres in Hull since 1970 — we'll get you the right ones.