Quick one lads, noticed tyre pressure from cold dropped to 29psi, they were 32psi from factory. Went to pop some air in and the machine said I was at 31psi, added a little all round so the machine read 32psi. Car still shows 29psi when cold and goes to 32/32psi when warm. Do I go by the machine or the onboard TPM computer? First time needed to add air btw.