I did mine yesterday with letting pressure out, It gives you 2 mins to cover all four so best to have valve caps off before you start. It ask what the pressure should be in them then you hit start and my horn honks twice, went to driver side front (4 tires) the drivers side back then passenger side back and passenger side front. just took small blade screwdriver and depress the valve and let air out till it honks then move on to next, once the last on is done it will honk twice . the refill to spects that you entered as the correct pressure it should have. Menu on the screen not lay out as well as it could be.