In general, tires are typically manufactured on a large scale through the build up of various layers onto a tire forming drum. The layers may include e.g., a carcass and other materials that provide the structure of the tire. The sides of these layers are turned up to create a toroid in the form of an uncured, tire intermediate. A layer or portion of tread rubber is then added to the tire intermediate to create what is sometimes referred to as a green tire. The green tire is subsequently cured by the addition of heat and pressure in a curing press.
The walls of the curing press typically include mold features for molding a tread design or tread pattern into the tread portion of the green tire. These mold features may provide e.g., tread blocks of various shapes and configurations with one or more grooves separating the tread blocks from each other. Various sipes or lamelles may be added into the tread blocks as well.
With aggressive tread designs, challenges to tire uniformity can be encountered in the conventional manufacturing process summarized above. As used herein, “aggressive” refers particularly to tread designs having deep (along the radial direction) and sometimes large tread blocks along the tread portion of the tire. Such designs can be commonly found, e.g., in military vehicle and off-road vehicle applications. In the manufacture of such tread designs, a large amount of the tread rubber from the tread portion of the green tire must be forced into mold features such as the cavities or apertures that create the tread blocks. Accordingly, a substantial amount of pressure is applied to displace this tread rubber and mold the tread features.
Unfortunately, this required displacement of the tread portion to form the tread blocks can also cause undesired displacement of one or more the layers of the green tire that are located next to the tread portion. For example, the carcass and/or other layers can also be displaced to create local effects such as waves, bumps, undulations, or other undesirable irregularities that make the tire non-uniform along the circumferential and/or axial directions. Breaking belts can also be distorted the displacement of the tread portion. Such non-uniformity can create undesirable endurance problems for the tire by e.g., creating areas where unwanted temperature increases can occur during tire operation and thereby effecting tire endurance.
Accordingly, a tire that can be manufactured with an aggressive tread pattern in a manner that can reduce or eliminate certain non-uniformities would be useful. More particularly, such a tire that can be manufactured through a method that can help eliminate undesired displacements of various layers of the tire during the molding process would be beneficial. Such a tire and a method of manufacture that can provide improvements in endurance would also be beneficial.