How to Measure for a Perfect Fit Wheelchair wheel sizes generally range from 20"-26" when measured across from one side of the wheel to the other. The spokeguard from CoolHubcaps.com will be slightly smaller than this measurement so that it fits snugly up under the push rim. To place an order for a spokeguard you will need to know two measurements: The wheel's overall size, and the interior diameter of the wheel. To confirm the correct size for your order we recommend you measure your wheels as follows: Meaure the overal diameter of your wheel - from one edge all the way across to the other side. (Most wheels have this measurement printed right on the tire). This measurement should match the mesaurements in RED in the picture below. Measure the interior diameter of the wheel from just under the push rim on one side of the wheel all the way across to just under the push rim on the other side of the wheel. This measurement is shown in BLUE in the chart below.   Spokeguard Sizing Chart Wheel size is 26 inches across Interior diameter is 22 inches across (55.9 cm) Wheel size is 25 inches across Interior diameter is 21 1/2 inches across (54.6 cm) Wheel size is 24 inches across Interior diameter is 19 1/4 inches across ( 48.9 cm) Wheel size is 22 inches across Interior diameter is 18 1/8 inches across (46.04 cm) Wheel size is 20 inches across Interior diameter is 15 inches across (40.1 cm) Wheel size is 12 inches across Interior diameter is 8 1/4 inches across (21 cm) If your chair is a standard size, the interior diameter measurement you come up with when you measure from push rim to push rim will be as listed in this chart. If your measurements differ from this sizing chart - please contact us and we'll make sure you get the right size for your needs. What Size Should I Select for the Interior Hole? Next you need to decide on the size of the interior hole for your spokeguard. The default size is 4 inches (10.2 cm) across. This accomodates most wheelchair wheel hubs. However, if you'd prefer a 6 inch (15.2 cm) or larger hole - no problem. Just let us know what size you need.