Tractor tires are often filled with a mixture of water and calcium to increase traction, reduce the center of gravity, and prevent the rear tires from lifting off the ground when lifting heavy objects or adding bucket loaders and other accessories to the front of the tractor. Calcium chloride is a common choice for this mixture, as it resists freezing to around -50°F. However, it can be known to rust wheels, so it is important to consider the long-term effects of using this material. Wheel weights are another option, as they are counterweighted plates mounted on a tractor tire.
Foam padding is another option for filling tractor tires, as it weighs up to 50% more than water by volume and offers an anti-puncture tire. However, this option can be expensive and may affect the “ride quality” of the tractor at higher speeds. Additionally, it is not possible to make future tire pressure adjustments when using foam padding. When considering what tractor and machinery to buy, it is important to follow the recommended pressure and ballast settings found in the tractor manual in order to get the best performance out of your tractor and ensure that you don't void any warranties.
YouTube videos may provide homemade methods for making foam on tires, but if you really want to load a tractor tire, it is best to go to a dealership and do it professionally.