  We investigate Weyl semimetals with tilted conical bands in a magnetic field.
Even when the cones are overtilted (type-II Weyl semimetal), Landau-level
quantization can be possible as long as the magnetic field is oriented close to
the tilt direction. Most saliently, the tilt can be described within the
relativistic framework of Lorentz transformations that give rise to a rich
spectrum, displaying new transitions beyond the usual dipolar ones in the
optical conductivity. We identify particular features in the latter that allow
one to distinguish between semimetals of different types.
