Many cars do have different tyre pressures for different loads, but the situation is slightly different with some electric vehicles. With a heavy battery pack permanently on board and low rolling resistance a key factor in boosting range, it is likely that the single tyre pressure setting is on the high side to compensate for the load and maximise efficiency. In addition the MG S5 has a relatively modest maximum towing capacity of 750kg, which prohibits increasing the gross vehicle mass to the point where a higher tyre pressure setting would necessarily be required.