Rubber is incoherent film, with terrible, halting dialogue, sketchy pacing, cardboard characters and no real plot to speak of.
Rubber is an incredibly enjoyable film, which leaves the viewer satisfied, and the critic struggling to find anything to criticize. The main character is extremely well portrayed, and very easy to identify with.
Ok, my little point/counterpoint above doesn't work so very well, but neither does the film. Except that it does. Let's just come clean, shall we?
During the introduction of the film, a police chief gives a lengthy speech about how none of the best movies make sense. "No reason" is established as the modus operandum, which validates the very surreal entry of the character into the film; he arrives in the boot (trunk) of a car, which proceeds to knock down roughly ten flimsy chairs, arranged across the road in no order, before exiting the trunk of the car and swapping his cop sunglasses for a glass of water. Then he gives the speech.
It's important to establish that the film's objective is "no reason," because the rest of the film is just as self-referential and surreal. An audience watches the action, as if watching the film itself, via binoculars, and comments on the proceedings and their own situation regularly. There are plenty of lessons you could take from the meta-film about film and hollywood in general, but of course the "no reason" mandate means that the film doesn't need to validate or prove any of them.
But what's the film about? Well, I suppose that's a fair question, and I'll give you the answer, although it may not help you much. Rubber is about a tire that comes to life, and seems to want to destroy everything. Fortunately for the tire, it has psycho-kinetic powers (a spectator who calls the tire 'telepathic' is quickly corrected by another spectator) and it uses them to go on a killing spree, destroying animals and any humans who offend it. It develops some kind of fixation on one traveler, and begins to follow her, while the police try to find the killer and while their chief tries to keep the illusion of the movie alive for the spectators.
There's plenty more I could say to explain, but I suspect I've said too much already. Rubber defies explanation, rebelling against the need to be defined by meaning or message. By doing so explicitly, it sets its own conditions in such a way that it can't possibly fail, except maybe by being too coherent. Fortunately, it manages to sidestep that bullet.