Share 'Are the Dugast Rhinos directional?'

Do the Dugast Rhinos have to be glued on with the tread facing a certain direction for the rear and for the front wheel?  I looked on the sidewall and the tread and there are no directional markings like most tires. Anybody know? http://ep.yimg.com/ca/I/cyclocrossworld_2117_11132196