There are a number of different types of ride-on fire trucks appropriate for all ages. Toddlers can start out with the Fisher-Price Little People Build 'n Fun Fire Truck. These are specifically designed for toddlers and are easy for them to use. Some of these ride-on trucks might need to be put together so be sure to check the instructions.
Older children will probably love the Little Tikes Spray and Rescue Fire Truck. Even I'm impressed with this one. Not only can your child ride in it they get to fill the water tank and spray things. How much fun is that!
Another favorite is the Little Tikes Ride 'N Rescue Coupe. This one is cool because it has an electronic microphone with flashing lights. What kid doesn't like to make a lot of noise!