Tires are fine. Run those if they're not dry rotted. If they're tube-type tires, you can run them even if they
are dry rotted.
Not sure who manufactured the kart but those side bars or "nerf bars" are indicative of it once having a fiberglass or plastic car body on it at one time.
I think it's a Fun Wheels, Inc. kart chassis....or close to it. Here's one similar: