On motorcycles and some sports cars, spokes are used to replace the wheel disc, which connect the hub and rim. Tires are put on the wheel rim. In modern cars, two types of rims are used: inseparable, with a small outer diameter, mostly in passenger cars, and separate, usually consisting of two parts, used in trucks with large diameter and wide wheels. In order to enable the installation of tires, non-separable rims are usually made as recessed. When the tire is fitted, the rim is inserted into the rim recess, whereby the remainder of the tire can be easily moved over the rim flange. On trucks, the tire is fitted to the separable rim after the flange has been removed (rim flange), which is held in place by a circlip. Sometimes a separable rim has two parts: subtracted and basic. Tires are put on the main part of the rim, and it is fastened by a removable part, which (is attached to the base with bolts and nuts. These screws are located on the outer periphery, farther from the center of the circle. The rims are marked with three symbols: the first number is the nominal diameter of the rim in inches, the second numeric symbol - indicates the width of the recess, finally, the third letter symbol - the shape of the rim. E.g. the Polish Fiat 125P car is equipped with disc wheels with 13 rims″X4 1/2 J. There is a hole in the rim for the inner tube valve. Edges of recessed non-separable rims, intended for tubeless tires, are smoothly machined on the inside to ensure a tight connection between the tire and the rim.