Abstract: A studless tire comprises tread blocks having a narrow-width center portion, a heel-side increasing-width portion and a toe-side increasing-width portion, wherein the axial width of the block becomes minimum in the narrow-width portion and increases toward the heel edge and toe edge in the heel-side and toe-side increasing-width portions, and the minimum width in the narrow-width portion being in the range of from 0.5 to 0.9 times the average of the maximum width in the heel-side increasing-width portion and the maximum width in the toe-side increasing-width portion, whereby the stress produced in the block rubber when a braking force or driving force acts thereon increases the apparent block rigidity to decrease the block edge lifting and thereby uneven wear can be decreased.

Abstract: An automatic initialization method including the steps of: measuring and monitoring acceleration of a vehicle in a lateral direction, defining correction values for each tire of the vehicle, and obtaining baseline values under normal pneumatic pressure conditions by using only data of angular velocity of rotation of each tire when the acceleration of the vehicle in the lateral direction ranges from -0.03 g to +0.03 g, when the steering angle of the vehicle ranges from -15.degree. to +15.degree., or when both the lateral acceleration and the steering angle are in the specified ranges. In the method of the present invention, only the data of angular velocities of tires is automatically picked up in the optimum driving status and initialization can be performed with high precision.

Abstract: A method for detecting a deflated condition of a tire, comprises the steps of (a) detecting the angular velocity of each wheel, (b) producing a signal proportional to the angular velocity detected, (c) detecting acceleration of the vehicle in a forward or backward direction, (d) obtaining a speed of the vehicle in the forward or backward direction by integrating the detected acceleration, (e) producing a signal proportional to the obtained speed of the vehicle in the forward or backward direction, and (f) arithmetically processing the signals produced in steps (b) and (e). In step (f), the angular velocity of each wheel at the speed in the forward or backward direction obtained in step (d) is obtained from a normal wheel angular velocity table previously prepared; and the result is compared with the angular velocity detected in step (a), and if the difference therebetween is within the range of 0.05% to 0.60%, a device for warning of a deflated tire is operated.