Tire used in winter

#The present invention relates to a winter tire capable of enhancing driving-in-snow performance.

#In the case of a pneumatic tire used on a snow road and a frozen road in winter (“winter tire”, hereinafter), emphasis is laid on the driving performance on an especially slippery frozen road. More specifically, there is employed a method in which a land ratio of a tread surface is increased to increase a ground-contact area, or a method in which a tread central portion having long ground-contact length in a tire circumferential direction is formed with a rib-like land on which a sipe is disposed. In any of the methods, however, the driving-in-snow performance, especially the driving performance on a deep snow road is prone to be deteriorated.

#The present invention has been accomplished in view of the above-mentioned problem, and it is an object of the invention to provide a winter tire capable of preventing the driving performance on a frozen road from being deteriorated, and capable of enhancing the driving-in-snow performance, especially the driving performance on a deep snow road.

#FIG. 1 is a development view of a tread pattern of a winter tire showing an embodiment of the present invention.

#FIGS. 2(A) and (B) are partially enlarged views showing other embodiments of a rib portion.

#FIGS. 3(A) and (B) are sectional views for explaining a groove edge line.

#An embodiment of the present invention will be explained below based on the drawings.

#FIG. 1 is a development view of a tread surface of a winter tire (simply “tire” in some cases hereinafter) of this embodiment. A tread surface 2 is formed with a central vertical groove 3 which continuously extends on a tire equator C in a tire circumferential direction. Inner vertical grooves 4 and 4 and outer vertical grooves 5 and 5 are formed on opposite outer sides of the central vertical groove 3.

#In this example, rib portions 6a and 6b which have sipes S . . . and which continuously extend substantially in the tire circumferential direction are formed between the central vertical groove 3 and the inner vertical grooves 4 and 4, respectively. The expression that the rib portions 6a and 6b are continuous substantially in the tire circumferential direction includes, as shown in FIG. 2, a case (FIG. 2A) in which the land is completely divided by a thin groove G1 having a groove width of 3 mm or less which does not substantially hinder the continuity of the land, and a case (FIG. 2B) in which a thin groove G2 which is terminated before it divides the land is provided.