A roller, in particular an expander roller, for a web-processing machine, has a support core, which is braced in the region of both its ends via a respective bearing arrangement, and an outer covering, which in its axially central region is braced in a radially fixed manner in relation to the support core and in the region of its two ends is braced in a radially displaceable manner in relation to the support core by a respective additional bearing arrangement, whereby the radially extending center plane of both the support core bearing arrangement and the outer covering bearing arrangement lies axially within the outer covering. Preferably the outer covering is displaceable in this case in the region of its two ends respectively by an actuator arranged within the outer covering.