The bead is that part of the tire which contacts the rim on the wheel. The bead is reinforced with steel wire, and compounded by high strength, low flexibility rubber. The bead seats tightly against the two rims on the wheel to ensure that a tubeless tire holds air without leakage. The bead fits it tight, to ensure the tire does not shift circumferentially as the wheel rotates. The width of the rim in relationship to the tire are a factor in the handling characteristics of an automobile because the rim supports the tire's profile.
The sidewall is the part of the tire that bridges between the tread and the bead. The sidewall is reinforced with rubber and fabric plies that provide for strength and flexibility. The sidewall transmits the torque applied by the drive axle to the tread in order to create traction. The sidewall, in conjunction with the air inflation, also supports the load of vehicle. Sidewalls are molded with manufacturer-specific detail, government mandated warning labels, and other consumer information, and sometimes decorative ornamentation.