Looking at the manual for my old Kity 636 there are 3 different wheels you could be referring to (although the bed-raising one for the thicknesser is the only one designed to be taken off) so I expect the 635 to be similar design. It might be easier to say what fitting the wheel has to adapt to: e.g. an 8 mm splined shaft or a 10 mm square drive, etc. As it is made in France it will certainly be metric.