set the tire on a bucket and seal one side and pump it up. If it's on the tractor then thats another issue. Are the wheels off ? I always put the valve stem on the inside of the front wheels and the backs you have to put the stem on the outside, thats the way they mount. you can spray ether in the tire and use a long BBQ liter and blow them on I don't recommend it but it does work and hurts your ears LOL . the best way is to get tubes. I wipe mine with winter green and let them set a few days that relaxes the side wall and mounts Farly easy. Believe me some things are just a PITA and thats one of them in life. one thing I did try years ago was to wipe them in side with vasaline and heated them up with a ready heater , that made them flexable and it worked out well too