There are three tread patterns or tread designs used on naval aircraft. They are plain, ribbed, and nonskid. A plain tread has a smooth, uninterrupted surface. A ribbed tread has three or more continuous circumferential ribs separated by grooves. A nonskid tread is any grooved or ribbed tread. Other tread designs may be provided under specific circum-stances or as required by applicable MS standards or drawing. The most common design used on naval aircraft is the ribbed pattern.

The tread construction will usually be one of four types. Other tread types may be necessary for specific circumstances or as required by military standards, such as ice and snow treads.

NOTE: Additional safety precautions are required in handling ice and snow treads.

Rubber tread. A rubber tread is constructed from 100-percent new (no reclaim) rubber. It maybe new natural rubber, new synthetic material, or a blend of new material and new synthetic materials.

Cut-resistant tread. A cut-resistant tread has improved cut-resistant properties that are imparted to the tire by incorporating a barrier into the undertread that resists penetration of cutting objects.

Reinforced tread. A reinforced tread is constructed with fabric cord or other reinforcing materials as an integral part of the tread. See figure 11-11.

Reinforced cut-resistant tread. A reinforced cut-resistant tread combines the features of both the cut-resistant and reinforced-tread designs.

Reference to the number of cord fabric plies in a tire has been superseded by the term ply rating. This term is used to identify a tires maximum recom-mended load for specific types of service. It does not necessarily represent the number of cord fabric plies in a tire. Most nylon cord tires have ply ratings greater than the actual number of fabric plies in the cord body.