A pulsed through-transmission ultrasonic non-destructive inspection of the internal structure in a tire wall is effected. The ultrasonic inspection is preferably carried out through the walls of a rotating inflated tire with the ultrasonic transducers being automatically moved toward the inner and outer tire wall surfaces to optimum relative distances of separation during an inspection cycle. The transducers disposed inside the inflated tire are preferably mounted for automatic retraction into a protected space during tire mounting and demounting operations. Such ultrasonic inspection techniques may be combined with conventional tire buffing methods and apparatus as practiced in tire retreading operations.

A machine is shown for conditioning a tire carcass for recapping wherein the tire is rotated while the crown is rasped to size and then a feeler is dropped onto the rasped crown surface while the tire continues to rotate. The feeler rides on this rasped surface to control the application of power driven shoulder rasping means to the carcass, the shoulder rasping means being operative on the opposite sides of the feeler to condition the shoulders for further processing. Adjustable guide means are shown for directing the paths of movement of shoulder rasping means to cause them to move in a desired pattern over the respective shoulders with which each shoulder rasper is made to cooperate.

An improvement in a tire siping machine which has a spirally threaded drum mounted for rotation about a first axis, a knife projecting from the drum for cutting a tire brought into engagement with the drum, and an arrangement for supporting a tire in engagement with the drum. In accordance with the improvement of this invention, a shaft defining a second axis about which a tire rotates during drum engagement is supported for linear movement laterally relative to the drum while maintaining a constant predetermined skew relation between the axis of the shaft and the axis of the drum.

A machine for retreading worn-out pneumatic tires comprises a chuck which is adapted to support a tire to be retreaded, an arrangement for rotating the tire, a peeling arrangement for removing the worn-out tread, a finishing arrangement for preparing the surface of the carcass for application of a new tread ring thereto, an arrangement for expanding the new ring and positioning the same on the carcass, and an arrangement for pressing the positioned tread ring against the tire, all of the arrangements being mounted on a common support with said chuck either axially or radially of the same for selective sequential movement toward and away from the tire to be retreaded.

Used and/or scrap pneumatic tires may be used for making wheels and pulleys for low speed, low load and low cost applications, the bead of the tires being utilized as the means mounting the tire, the bead being deformed to a generally polygonal shape. When plates are substituted for spokes on the wheels, low cost tumblers are produced.