Pneumatic Tires vs. Flat Free Tires Do you currently have a cart or wagon that is in need of new tires? I mean, why else would you want to know the difference between pneumatic tires and flatfree tires? Whatever the case may be, there are a number of differences between the two tires, the first being the name. Something that is “pneumatic” means it is operated by gas or air under pressure, which would give you a hint of what a pneumatic tire is. If you guessed an airfilled tire, you’d be right.