Can you change snowblower pulley size?

It depends on the snowblower, belt type and what you arer trying to achieve by making the change. The replacement pulley(s) will have to be the same shaft id as the original to start. Next make sure that there is room inside the snowblower for the new pulley. Thirdly the belt may have to change depending on the pulley size that you choose. There are many different pulley types and sizes available. Be aware of the changes that are made because they can decrease the snow throwing ability and also affect the drive speed and vice versa.