[ejdd]

Hey guys, wondered what you're thoughts are with this. I dont know if its related but the temps here have started to increase by 20 degrees Celsius so -1c to 20c in one day. Usually that causes havoc with the tire pressure and im used to that in previous cars. This is a bit different though.

Monday afternoon i jump in my car after work (so its the warmer part of the day) and the TPMS alerts on 1 tire. 23psi instead of the usual 30psi.
I pull over, put my hands over the wheel - feel nothing protruding (but this was far from thorough). Get the pump out and put it up to 30psi, go for a drive and tpms records all 4 tires normal, slowly all reaching 35psi as the wheels warm. Great!

Wake up next morning and TPMS reports tires all fairly even 29-30PSI
I drive to Work stay for 9 hours.
I drive home and the tire is a little low at 28psi so i top up a little, thinking as i pumped it up before when the tire was warm it might fluctuate a little.
I come out this morning and the same tire is at 20psi, checked with a manual gauge, when all the others are 30psi. I pump up and start panicking.
So my thoughts are:
Most likely I have a puncture in the wheel that i cannot detect (yet)
or
faulty valve?
or
damaged rim - although there is no visual damage and dont drive on potholed roads or anything?
or
someone is playing a nasty joke on me and letting down one tire where i park it. Yes that thought has also crossed my mind.
or
could the temperature change have affected the way the tire is sitting on the wheel or something?

Any ideas? I've done 1800kms so its basically new.

Thanks

 

[RussellHodgson]

Can you remove the wheel and submerge it in water? That would let you know if you have a leak and if so where.

If you can't do that then you could try spraying it with water on key points you think may be leaking - like the valve, etc.

 

[Porsche2018]

That seems to be wide variation and sounds like the TPMS may be malfunctioning. This is an issue the dealership should be able to resolve for you.

 

[ZuffenHouseRules]

I had similar symptoms over several days (and theorized similar causes) but it proved to be a nail (which I eventually found).

Don't make the mistake I did of shooting 'just a little' fix-flat in there as a temporary precaution, it requires replacing the tire....expensive.

 

[GregW]

If both the TPMS and a gauge are reporting that the tyre is deflating, it almost surely is damaged. While Porsche recommends only replacement, my dealer says some centre-of-tread punctures can be fixed. Mine couldn't.

Get it checked before you end up with serious damage and possibly stranded.

 

[My718isPorsche#5]

First thing to do is check that the valve stem core is tight. Remove the cap & put some water or spit on the end & see if you get a buble. Do this at the warm part of the day.

 

[ejdd]

Thanks for all the ideas. Lost 6psi overnight with a manual gauge check versus none on the other tires. Im booked in with Porsche Vancouver next Wednesday and i bought the add-on package that covered tire damage, so hopefully free tire replacement. They were a little cagey, on whether or not i could prove it was actually damaged if i couldnt find a nail etc. First they said they only covered nail damage, then i had to send them my "VIP Protection Plan" agreement which states:

Tires - we will fix or replace the flat tire if the tire is damaged without air. Tires cannot be repaired on a sports car. Only the damaged tire will be replaced. Must be above the safety tread.

This after dropping over $4k for it I found the semantics of what constituted "damage" to be more than annoying. He said if it's not damaged you'll have to pay for the tire. My Reply - If it's not damaged why would i need a new tire?!!?

I can understand if its possibly the rim (not covered) or even the valve (debatable) but if the tire is losing 5-10psi per day and its not the other 2, regardless of physical looks - the tire is damaged.

AANNND - the weather has turned beautiful here finally - perfect for a long drive this weekend - its killing me!!! ;-D

 

[nineball]

Can you remove the wheel and submerge it in water? That would let you know if you have a leak and if so where.

If you can't do that then you could try spraying it with water on key points you think may be leaking - like the valve, etc.

i've found much better results with a little dish soap mixed into the water. it breaks the surface tension and makes bubbles much easier to spot.

 

[Porsche2018]

@ejdd, never do those dealership "package" plans ever. They are designed, in most cases, to take your money at closing then it's hard to get them to honor it because there is always the "Fine Print". Others, love to do the dealership packages but I never have and never regretted or more importantly needed it.

 

[ejdd]

yeah they got me.

 

[ejdd]

it was a nail