245/40 R18 Tyres Explained

245/40 R18 is a common tyre size for performance and premium cars, larger hatchbacks and sporty estates. The numbers are simple. 245 is the tread width in millimetres. 40 is the aspect ratio, so the sidewall height is 40% of 245mm (about 98mm). R18 means the tyre fits an 18 inch wheel. You'll find a wide choice in this size. Premium brands include Michelin and Continental, with sport and all season options. Bridgestone, Pirelli and Goodyear also feature. mid range names such as Hankook and Kumho offer dependable performance. Value options include iLink, Tomket and Nankang for budget buyers. If you're after a sport tyre, consider the Michelin Pilot Sport 5 or the Continental SportContact 7 in 245/40 R18. Confirm this is the correct size by checking the tyre sidewall, the driver's door sticker or your vehicle handbook, or enter your registration for exact matches.

The first 3 sets of numbers that you will see when reading a tyre size tell you the width, profile and diameter of your tyre. In this case, for the tyre size 245/40 R18 this is broken down as follows: 245 - the width of the tyre in millimetres. In this case 245mm wide. 40 - the height of the sidewall as a percentage of the width. In this case 40% R18 - the diameter of the tyre's inner rim in inches. Essentially what size of wheel this is intended to be fitted onto. For this size, that is a 18 inch wheel

If you are looking for the recommended tyre pressure for 245/40 R18 tyres, you will find that this will depend on the manufacturer and model. Each vehicle manufacturer has their own tyre pressure recommendation for their model, that will deliver an optimal performance for your vehicle. Check the following if you are unsure what the correct tyre pressure is for your 245/40 R18 tyres Tyre label - this is often the best place to find your tyre pressure information. It is located on the door jamb on the driver’s side of the vehicle. It is a small rectangular label that provides the driver with the recommended tyre pressure and tyre sizes. Vehicle handbook - Quite often the vehicle handbook with contain a section that relates to the technical details for the tyre. This should include the required tyre size, load rating, speed rating and recommended tyre pressure.

The sidewall height of a 245/40 R18 tyre is calculated by using the profile information of the tyre size. In this instance 40. This tells us that it is 40% of the tyre's cross-section width. When looking at a tyre, the sidewall height is the distance between the tread line of the tyre and the rim line. Given that this tyre size has a cross-section width which equals 245mm, we can work out that the sidewall height is 40% of 245 – this comes to 98mm.