Wheels and tyres are different. The wheel is the round metal structure that attaches to the axle and hub. It is the metal part that the tyre goes on. The tyre goes on the wheel. The tyre is made from a rubber compound. The tyre size is dependent on some aspects of the wheel size. Tyre shops use the tyre size on the sidewall of the tyre, such as 225/45 R17, to determine the tyre size. Here’s what the tyre factory details mean. The ‘225’ is the width of the tyre sidewall measured in millimetres. The ‘45’ relates to the height of the sidewall. The number is the percentage of the tyre width. In this case, the sidewall height is 45% of the tyre width. A high-profile tyre makes more contact with the road surface and gives more comfort and fuel efficiency. Low profile tyres offer better grip, handling and braking. The letter signifies the tyre construction. The most common type is ‘R’ for radial construction. The final number, 17, is rim size. This is also called the wheel size. Wheels and tyres are different, but the size of the wheel impacts the size of the tyres.