225/45 R18 Tyres Explained

225/45 R18 is a common tyre size for many family and compact executive cars. The numbers tell you the tyre dimensions. 225 is the tread width in millimetres. 45 is the aspect ratio, so the sidewall height is 45% of 225mm (about 101mm). R18 means the tyre fits an 18 inch wheel. You'll find this size across a wide range of vehicles that need stable cornering and a comfortable ride. It's available from premium manufacturers such as Michelin, Continental, Pirelli, Bridgestone and Goodyear. mid range choices include Hankook, Kumho, Falken and Yokohama. Value options on the page include Wanli, Tomket, Mazzini and Royal Black. For performance or higher grade touring, models like the Michelin Pilot Sport 5 and Continental EcoContact 6 are offered in 225/45 R18. Confirm this is right for your car by checking the tyre sidewall, the driver's door sticker or your vehicle handbook, or enter your registration for exact matches.

The numbers 225/45 R18 are 3 very important pieces of information in regards to a tyre's size. They tell you the width, profile and diameter of a tyre. For a tyre that is 225/45 R18 this information can be broken down into the following: 225 - the width in millimetres of the tyre. In this case 225mm wide. 45 - the height of the sidewall as a percentage of the width. For this tyre that is 45% R18 - the diameter, in inches, of the tyre's inner rim. Letting you know what size of wheel this tyre should be fitted to. For this size, that is a 18 inch wheel

If you are looking for the recommended tyre pressure for 225/45 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 225/45 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 225/45 R18 tyre is calculated by using the profile information of the tyre size. In this instance 45. This tells us that it is 45% 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 225mm, we can work out that the sidewall height is 45% of 225 – this comes to 101.25mm.