Welcome and thank you for your service in the Men's Department of the Navy.
Solid tires are available for that mower if your current tires are frequently airing out.
Make sure the wheel is very clean and cut or scratch free in the bead area. If its rusty or rough, the air seal can be a major hurt.
Put the wheel in a vise, holding it in the jaws by the hub. This ought to be a 'drop center' wheel, so that means one part of the tire bead needs to be in the central part of the wheel rim (about 1/2 way across when you start. Use dish soap to lube the tire bead. It will make the job much easier as you try to slip the bead over the rim. You can use a couple of large flat head screw drivers to begin the process. Hold the tire so that one section is at or within the drop center part of the wheel. Use the screw drivers to pry the tire bead up or under the wheel rim. The opposite part of the tire bead will try to slip off and follow you around the wheel. This can cause you to use a lot of foreigh language. Instead, use a Vice Grips or several of them to lock the tire bead in position while you go for the next pry area. Eventually you will arrive at a point where the tire bead will fully slip onto the wheel.
Do this one side of the tire at a time. If you want to avoid future headaches and cost, slip a tube into the tire while you have just one side mounted. Try to line up the air valve with the hole in the wheel at this stage of tube installation, and don't cut the tube with your tools.
The next incident of hurt will be trying to air up the tire. These small tires resist airing up when tubeless. If you put a tube in, use the Vice Grips to hold the stem in place at a good length so it doesn't slip into the tire chamber. Don't hurt the threads on the stem. Remove the valve core from the stem (using a special tool or a special cap made for such a job) so that the maximum air flow rate can be utilized. Then get some helping hands so that you can hold the air chuck into the stem and manipulate the tire carcass to try to seat the beads enough to trap some air in the tire. When it starts inflating, stop and reinstall the valve core. Then set the pressure and put the wheel back on and go mowing!
First time could take you a few days. Second one will go more quickly.
A lot of people waste time when they try to remove the old tire. Breaking the bead loose from a rusty wheel is a major issue. I use a die grinder and a thin wheel to dismember these prisoners every chance I get. Make them cooperate or else. You know, Allen Hackbar and all that crap.
