Today, 24.10.18, I filled my car with diesel as usual at Sainsbury's in town petrol station and checked my tyre pressures. I was unhappy with the tyre pressure machine as I kept getting different readings having set the automatic pressure set. I reported my concern to the cashier and then I checked my tyre pressures against a calibrated pressure pump For the front (33 psi) my reading was 28 psi for both tyres for the rear (30 psi) the readings were 22 & 28 psi.