disclosed is a wheel having two staggered rows of surface - gripping , radially - yielding feet . when the wheel encounters an obstacle , a spring compresses , thereby permitting the feet to deflect and absorb shock that would have otherwise been imparted to the vehicle . while travelling on a smooth surface , the feet deflect an amount depending upon the load carried by the wheel . since the shock absorbing spring is recessed in a cavity in the foot , the distance that a foot can deflect is increased .