Car Tyre Pressures

[kenny1234]

I have had a Hyundai 120 for a couple of years---on the occasions that the tyre pressure warning light came on I put some air in to the required amount. I got used to not seeing the warning light go out straight away--but after about 1/2 a mile drive. Two days ago I put some air in all the tyres(because the warning light had come on), but the light didn't go out until the next day!---just curious

[gingejbee]

After having topped the tyres up, it does take a reasonable driving distance (not time) for the TPM system to re-set to the new, higher pressure.

I never rely on the TPM system to alert me to lower pressures... I always check at regular intervals with a decent gauge.

[Electrochem]

Did you check the pressures with an accurate gauge and when the tyres were cold?

[bhg481]

Different car manufacturers use different methods for detecting tyre pressure loss. Some use the difference in rotation speed of wheels (a flatter tyre will cause the wheel to rotate more quickly); if that's the case with Hyundai you will need to travel a reasonable distance for the car to detect it reliably as it needs to even-out the effect of cornering.

[kenny1234]

The point I was trying to make(which i think you have answered) was ----is there quite a difference in time sometimes, before the warning light goes out. i.e. it can be 3 minutes or 2 days ?

[Hopkirk]

Check the manual to see if you have to reset the system. On some manufacturers you have to do that whenever you top up the tyres.

[Hopkirk]

A quick Google suggests you are right, on your car you just have to drive it.

Perhaps it thinks you aren't inflating them enough. A drop in temperature will cause the pressure to drop.

Alternatively perhaps you have a leaking tyre.

[kenny1234]

Hi Hopkirk

I don't need to reset myself---It does go out itself----I just wondered why the difference in time when this action  takes place (after the correct pressures have been inflated)

[Zacs-Master]

Changes in temperature can affect the sensors. Mine gives a low tyre pressure warning when it's really cold. Maybe there was a temp change just after you pumped the tyres up confusing the sensor?

[Hopkirk]

You shouldn't really ever be seeing a low pressure warning. It suggests a fault with a tyre, a fault with the system or it wants you to have higher pressures in your tyres.