Tpms wrong pressure.

[andrewjoseph]

Hi peeps, had the new tekna cvt on Friday, then had to go to a cycling event over the weekend ( where it looks like someone keyed the side!). Review to follow.However, tpms is showing pressures as too high by several psi. the car was really well loaded with camping stuff so put rear pressures up to 38 psi as per placard on door pillar. tpms showed 44.Reduced rear pressures this morning to 30 and tpms shows 48!Tried recalibrating but no change.Any ideas?Thanks.

[AlleyCat]

What are you comparing the pressures with?Foot pump, digital gauge, the horrid things at garage forecourts?Obviously letting air "out" should bering the value down but i imagine ambient temperature and when the car was last driven and for how long will impact the readings also.Mine go up by about 4 or 5 PSI when i've driven on the motorway (according the TPMS).

[andrewjoseph]

Thanks, alley cat, used an old fashioned pressure gauge I've had for 30 years or more, then my new track pump for my bike. Then a digital garage forecourt pump, and this was almost exactly the same reading as on car tpms.So I need a new gauge for the car!.

[korky]

I agree that when on motorway the actual psi increases as expected really. What I want to know is how does the car know what the psi should be - is it set as default or does it detect weight etc and change