You can add water to your tractor tires in a few different ways. The most common and easiest way is to use a hose. Attach the hose to a water source and place the end into the tire. Fill the tire until it is full and then replace the cap.
Another common method is to use a 5-gallon bucket. Fill the bucket with water and then place it underneath the tire. Slowly open the valve and allow the water to flow into the tire. Once again, fill the tire until it is full and replace the cap.
If you have an air compressor, you can also use that to fill your tires with water. Simply attach the air compressor to a water source and turn it on. The water will flow into the tire and fill it up. Once the tire is full, turn off the air compressor and replace the cap.
As you can see, there are a few different ways to add water to your tractor tires. Choose the method that works best for you and your situation.