Had to buy steel wheels for my MTD blower as the others kept breaking the bead. These came with spacers. I can't tell if the spacers go on the outside of the blo9wer body or the inside. Sounds stupid, but can't tell.
measure your old hub inside to outside. if it is the same as the new ones you dont need the spacers. if the new wheels are narrower than the old put the spacer on the side it is needed. if the hub is shorter on the inside of the wheel put it there. if the hub is shorter on the outside, put the spacer there. the part number for the wheels probably covers many models. some need the spacer some dont. if you mean inside the blower housing as in not visible from operator position and only visible when you take the belly pan off........if there were no spacers inside the housing before there wont be any now.
a couple of pics of both sides of new and old wheels would determine for sure.