TPMS

The 1st coolish morning this morning (5°C) and within 100 yds of setting off the dashboard lit up with tyre pressure warnings. All tyres showing as 23 or 24psi on tpms. A short trip and the tyres were showing 24 or 25psi, warnings still lighting up the dash. I know that, when warm, the tyres are all where they should be - 26 or 27psi. Does this mean that every cool morning the dashboard's gonna be lit up for a few miles til the tyres get warm?

On my other car with TPMS I always end up putting a little bit more air in, in the winter months. As I understand it pressure and temp are obviously linked, so if at this time of year lets say the average daytime temp is 14 degrees C, i go to the garage on an average temp day and top my tires up to the recommended pressure and it then seems to be fine for the season. When we get to the warmer months I go and do it again and it invariably involves a little bit of air being taken out, but it works fine.

Mine did it a few weeks ago, since the tyres were blown up in the summer. I find the TPMS is good at telling which tyre is parked in the Sun.

Now it is going to be cold and dark all the time, they want topping up a bit.

Make sure the TPMS is set to "comfort".

Annoying isn't it? It keeps coming back and making the dash angry red- mine is angry red most of the time anyway with "Danger!-Danger! Crash imminent!" I'm glad it doesn't talk- or scream in fear :laugh:

It takes 10 minutes to go away, but comes on instantly too.


As an aside, my brother works for ATS, and he says company policy is not to blow up a tyre if it is more than 10% down, they are supposed to dismount it and check for internal damage. Considering you can loose 10% between yesterday afternoon in the sun and this morning with a cold snap, it seems a bit too 'Elf and Safety".

The pressure of an ideal gas is proportional to its Kelvin temperature, so the formula is


P2 = (T2 +273)/(T1+273) x P1

eg, 26 psi @ 25 degrees and now it is 2 degrees P2= 275/298 x 26 = 23.99 psi

This assumes you paid for the expensive dry nitrogen fill, it is probably miles worse with "ordinary" air all full of water vapour.

What's the actual Suzuki recommend PSI for tyres on the G4?
Only asking as if it's 26 psi as per G3 then a trigger level of 24 psi or just below on the TPMS is awfully close to normal operating pressure. I googled and the web (it must be correct :laugh: ) suggested a typical 25% from recommend pressure is the normal trigger point. So at 26 PSI that's 19.5 psi, or at 32 psi it's 24 psi - that's an interesting coincidence.
So is 32 psi correct operating pressure or have Suzuki incorrectly set the trigger point as per the Swift etc?
Just over thinking it for fun.
Mike

Strangely, I had a similar issue yesterday. Cold morning and expected first windscreen scraping of the winter. However, the school run was interrupted by lots of orange warnings about low tyre pressures. Suddenly all the tyre pressures were out of kilter by a few psig. Left car sitting for 3 hours to ensure tyres were stone cold. Checked pressures manually, 1.5 psig low on a couple, so re-inflated them, double checked pressures were to spec and reset the TPMS. Now no orange lights but according to TPMS I'm now running about at 1psig over spec! Good news is that all the orange warning lights have gone out.

So as a safety measure , or because modern man can't work a tyre pressure gauge,we now have a warning light...excellent .....BUTto make it not intrusive we now add more air than needed in winter reducing the tread area on the road when in the old days we reduced the pressures to expand the tread area....
PROGRESS,!