Pressure gauges
A quality air pressure gauge is recommended to check tire pressure. After checking the air pressure, replace valve cap finger tight.
Tread wear indicators
Tread wear indicators are molded into the bottom of the tread grooves. When tread depth is 1.6 mm (1/16 in.), the tread wear indicators will appear as a 13 mm (1/2 in.) band (Fig. 4).
Tire replacement is necessary when indicators appear in two or more grooves or if localized balding occurs.