Uneven tire wear is often caused by mechanical irregularities on your piece of equipment. During your prestart and post operations, inspect your tires for wear, as shown in figure 3-17. These conditions can be caused

Figure 3-18.-Directional mud and snow tread.

Figure 3-19.-Mounting of directional tread tire.

by improperly balanced tires, bad front-end alignment, or operating an all-wheel drive vehicle with the front-wheel drive engaged on hard-surfaced roads. This wear must be documented and turned in for repair.

TYPES OF TIRE TREADS

Tire treads are made for a specific purpose. The type of equipment you are operating and the type of job you are performing dictates what type of tire and tread you should use.

Directional Tread

The directional mud and snow tread (fig. 3-18) is of a V-design with large spaces between the lugs. The spaces between the lugs are kept free from snow because of tire rotation and flexing, therefore improving traction. A direction tire maybe mounted on the rim only in one way and delivers traction in one direction only. The point of the V-design must contact the ground first when traction is required. When directional tread tires are mounted on a dead or steering axle (unless the equipment is all-wheel drive), they are mounted so the open V meets the ground first (fig. 3-19). This type of tread is commonly found on graders.

Nondirectional Tread

The nondirectional mud and snow tread design (fig. 3-20) also has large spaces between the lugs. The lugs are placed perpendicular to the center line of the tire. This design provides good traction in both directions.

Cross-Country Tread

The cross-country tread (fig. 3-21) is the same as the mud and snow tread, except that the cross-country tread has rounded shoulders.

Regular Tread

Regular tread (fig. 3-22) consists of small spaces between tread patterns. This allows for a quiet ride and

Figure 3-21.-Cross-country tread.

Figure 3-22.-Regular tread.

safe operation on wet and dry roads. This tread is often used on modern highway-operated tires.

Rock Service Tread

Rock service treads (fig. 3-23) are characterized by narrow voids between lugs so that loose rock cannot be caught and tear the tread lugs loose from the tire body. This nondirectional tread design is used on tires for service on rough terrain.

Earthmover Tread

The earthmover tread design (fig. 3-24) is for tires used on heavy equipment working in areas, such as a borrow pit or off-road service.