Hi the size in the photo is measured manually with deviation (ranged) at 0.1-0.5MM. HOW TO MEASURE THE WHEEL CENTER CAPS Before you place the order, please check the tips of how to measure the right size of hub caps you want. It's better to use the Vernier to measure the sizes. 1. Measure the wheel center hole Please check the following bottom photos. There are total two sizes you have to measure. First is the Outer Diameter(O.D), second is the Inner Diameter(I.D). 2.Measure the old wheel center caps you have Please check the following bottom photos of the right method to measure the sizes of hub caps. 3.If you still do not know how to measure the size, you can ask the supplier of the wheel hub caps of the sizes, including Outer Diameter, Inner Diameter and Length