Realistically nothing happens. The pressure relief valve does not matter, as the track itself has to fail from the impact. Nobody is going to uniformly squeeze it to build pressure to make it rupture, where the valve would open. A fire cooking it for minutes means you are either already burned crispy or simply not near anymore. But in that case at least we get a nice explosion.

But really nothing happens, there is nothing to crush it. A bike will just give way and the tank flies off. You need either a ton of inertia behind it or 2 vehicles pancaking you.