You may find? You have to get some spacer to hub, small headed bolts for the fronts. These sit flush with spacer to allow the whell to mate to the spacer.

This happens if you wheels are not machined to allow the wheel bolts (now holding on your spacers) do not have enough room, to fit the bolt heads into the wheel recess.

On the 30mm rears the bolts will sit flush. On the 25mm the bolts well protrude by 5mm. You can either cut them down with an angle grinder, or buy purpose fit spacer bolts.