Airplanes need wheels for a few important reasons! First, when an airplane is on the ground, it has to roll around, just like your toy car! The wheels help it move quickly when it's taking off from the runway.
When the airplane is ready to fly, it uses its wheels to go fast and lift off the ground. Then, when it comes back to land, the wheels help it slow down and stop safely on the ground. So, just like you need wheels on your bike to ride, airplanes need wheels to help them start and stop flying!