This 2.50-4 or 2.80-4 size is often found on mobility scooters made by Pride, Amigo, and Bruno. How can you be sure this is the correct tube for your tire? Simply read the tire size off the side of your tire. If it says 2.50-4 or 2.80-4 this is the tube for you!
Even if you don't have a flat, it's always a good idea to keep a spare tire and tube on hand so that you can keep going.