Tyre pressure alerts haywire in extreme heat

[FLANEUSE]

Extreme Australian heat is playing havoc with tyre pressure alerts: really haywire. I was freaking out after several attempts to inflate and receive correct readings on screen, without success. Kind young man at Bridgestone Tyres Zillmere didn't charge me when he checked all pressures and did the water immersion test to detect slow leaks. All fine. Since then, some days it goes up and down depending on temperature or time of day. I've stopped worrying but have the offer to go back if I'm worried again.

 

[MG Clive]

Which MG do you have @FLANEUSE ?

 

[tsedge]

This is in the wrong forum, isn't it?

 

[MG Clive]

This is in the wrong forum, isn't it?

Yes, it'll be moved when we know which MG @FLANEUSE is referring to.

Edit Coulomb: Done.

 

[FLANEUSE]

Yes, it'll be moved when we know which MG @FLANEUSE is referring to.

I have an MG4 51 Excite

 

[ReintjeWA]

G’day mate! Yeah the TPMS will show different pressures as ambient temperatures affect the pressure inside your tyre. As a rule of thumb, as long as the pressure difference between cold and warmed up tyres is no more than 5 psi (or 0.3 bar) then she’ll be right.

If it’s more than this, it may indicate your tyres are flexing too much and generating heat, thus heating up the air inside the tyre, which will show as excessive increase in pressure when driving.

The tricky bit with the MG4 is that it won’t show you any pressures unless you’re driving, so if you want to check this make sure you check the pressures it displays within the first few minutes of starting driving. Mine normally take about 5/10 minutes to warm up and show my “warm” pressures.

The fluctuation between early morning and late in the arvo is also very noticeable, especially when one or two tyres have been sat in the sun for a bit, but again, as long as your total pressures stay above 2.5 bar (the car seems to trigger alarms around 2.4 bar from memory) you should be fine.

@Jamesrr did you get an over-pressure warning at some point? Or was that in one of my tyre-fever dreams?

If you’re looking for stuff relating to your specific model, they’re referred to on here as SE SR, just an FYI.

 

[Jamesrr]

@Jamesrr did you get an over-pressure warning at some point? Or was that in one of my tyre-fever dreams?

Yes. The tyre "over pressure" warning triggers at 3.4 bar (well not immediately at 3.4 but from 3.4 and before 3.5) At 3.5 there will be an over-pressure warning.

My experimenting* found 44.5psi the best "cold" pressure to get the best energy efficiency without hitting the over pressure level when they warm up.

Also note that it is the rear driving tyres that affect the energy efficiency the most. Make sure they're pumped up!


*With my new Pirelli Cinturato P7 replacing the original Turanza's that it came with.

 

[ReintjeWA]

*With my new Pirelli Cinturato P7 replacing the original Turanza's that it came with.

Did you stay with the factory size for your new tyres?

 

[Jamesrr]

Did you stay with the factory size for your new tyres?

Oh yes. 235/45R18.

 

[Sparky2]

Exactly the same thing happens up here in the Pennines in the Northern UK, except that it is the cold weather that confuses the TPMS sensors. Almost anything below freezing will prompt the car to tell you that the tyres have low pressure and need attention. If you stop after a few miles at reasonable speeds, the message disappears only to re-appear the next cold morning

If you are the sort of person who does not understand the relationship between air temperature and tyre pressure, you would be constantly pumping the tyres up in freezing cold weather