The easiest way I have found to remove tires from a snowblower yourself is first remove the bolt or pin holding the wheel on the axle.once removed let the air out of the tire , you can use a valve stem removal tool or a small jewelers srewdriver to remove the valve stem. I find using a bench vise (or a couple of strong feet) does the trick.Once the air is out of the tire insert the tire in a bench vise (making sure not to catch the rim just the rubber tire) slowly turn the vise and one side then the other will pop.Once this is done you can use a couple of flat bars or small tire irons or even a couple of large screwdrivers.Insert one bar under the lip of the tire then push down on the bar allowing the lip of the tire to come over the rim,next put the other bar about 2 to 3 inches away from the first and do the same thing and work your way around the tire,about half way around the tire will come off.Do the same to the underlip ,or go to your local repair shop and they will probably charge a few bucks to do this.