a thin , membrane - like cylindrical rubber tire curing bladder is provided with reinforcing cords wound in parallel spiral paths at any composite angle to the longitudinal axis of the cylinder . when installed on the centerpost mechanism of a tire curing press and inflated in the curing process , the bladder length increases due to partial and reversible straightening of the spirally wound cord reinforcement . this permits optimum fit of the bladder in the tire being cured with uniform controlled growth of the membrane . longer service life of the bladder is thereby achieved . the bladder is a good heat conductor inherent to its thin matrix , unlike previously known curing bladders .