Ideal MHD restricts both the current and the pressure which can be stably confined in aTokamak. A pressure profile optimisation is carried out for a variety of equilibria, whichinclude JET and INTOR-like plasmas, in order to obtain the maximum β which can be stablyconfined at constant current. The current is limited to a value corresponding to a safetyfactor slightly above 2 at the plasma surface. A simple scaling law is found that fits wellall the cases and which predicts a linear rise of 3 with the current.