The tyres in size 245/30 R20 are designed for passenger cars of a sports character. In the first position in the size, there is a tyre's tread width (expressed in millimetres). The next position is reserved for the tyre's profile height (which amounts 30% out of 245 millimetres of the tyre's tread width). The "R" means that the tyre has been produced in accordance with the rules of a radial technique. The last position is the exact designation of the diameter of the wheel's rim (in inches) which can be installed with the tyre in size 245/30 R20. You're welcome to do the shopping!