Patent ID: 6905564

Claim:
A process for creating controlled extension and retraction of a tire tread segment in a vehicle tire which comprises: providing a tire including a casing of steel and rubber having an outer peripheral surface and a tread secured to said peripheral surface and defining a ground engaging surface; forming a channel in the tread with side walls and a bottom wall, the bottom wall of the channel inset from the ground engaging surface; laying a non-adhering film on the bottom wall; laying an uncured rubber layer over the film within the channel, said layer having an outer surface inset from the ground engaging surface of the tread; curing the rubber and thereby bonding the rubber layer to the walls of the channel, the film preventing bonding of the rubber layer to the bottom wall to thereby form an expandable chamber between the layer and the bottom wall with the rubber layer then providing a continuation of the tread across the channel; and providing a controlled air inlet to the chamber for extension and retraction of the chamber for selective extension and retraction of the tread segment from the channel.