Mr Jones

I bought new Michelin PSS’s in December at the dealer and I’m finding that all 4 tires are slowly leaking and I can’t work out why. I got the dealer to do a quick check about a month ago and they couldn’t find anything and they said the valves etc were fine. But I’m still finding that they lose about 20 KPA/3 psi in a week. I even made sure I did the comparison at the same time, Sunday morning drove straight to the service station to check. The only thing I could think of is, could the wheels be cracked in some way? There’s no visible damage and I haven’t crunched them at all. Has anyone had any problems with leaking at all?
As per the placard on the car I’m running fronts - 290KPA/42 psi , rears - 300 KPA/43 psi.
I’m going back to the dealer on Thursday but any ideas are welcome.

Mort

You should probably buy yourself a tire gauge so you can check the car in the garage, or wherever it is parked, after it has sat for the night. Driving the car will warm the tires up and increase the air pressure and likely not the same amount each time. Tire pressure should preferably be checked cold before driving.

Those wheels have been known to get small cracks in them but all four at once would be unusual.

If you check the pressure at home carefully for a week and you are losing air then take the car to the dealer and get them to submerge them in a tub of water to locate the source of the leak(s).

Phil Chow

Maybe not sealed properly.

Have them take them off, and clean where the tire seals to tbe rim, and then re-use the black "Glue" like substance to ensure a solid seal.

C63-AMG

Also check the TPMS sensor. I had and issue with two of them when I replaced mine.

Roswell

Taking ur car to the dealership for tires was the first mistakes. Lol

Any good tire shop can remove ur wheels/tires from the car & submerge in a water tank & tell u right away if or where the leaks are.

tpliquid

might be the tpms

zcct04

US cars have a tire pressure monitoring system that lets you check pressures in each tire in real time on the dash. Not an option on Aussie cars?

nallishaw

Possibly the TPMS, they can be rebuilt with new seals and whatnot, very in expensive at places like discount tire, tire kingdom etc, Also be sure to replace the metal stems, I got all four at discount tire for 16 a piece, mine were slightly corroded and were causing a slow leak, this is not normally part of the regular rebuild kit, don't let them try to tell you that you need an entirely new TPMS module.

Mr Jones

In Australia we don't get the TPMS on our C63's. We get a system that compares wheel revolutions and relies on the fact that if a tire is low in pressure it has a slightly different diameter. As per this thread: https://mbworld.org/forums/c63-amg-w...ml#post6275886

Thanks for all your help. My car is at the dealer today getting checked out.

Roswell, I hadn't planned to buy the tires at MB and always thought they'd be hideously expensive but they ended up costing less than a reputable tire dealer I was going to get them from. Quite a surprise.

GRP

Dealer fitted PSS? My understanding was that MB dealers here would only fit same tyre as original factory oem which for us is the Continental. The price might have been cheaper than you were quoted by a tyre dealer but was probably much more than you would have paid from a grey importer and why not use a grey importer given that the tyres are made in France anyway. I have had excellent buying on fresh production tyres from Tyroola, Tempe Tyres and Tirerack (when the A$ was good against the US$).

On the other hand with new tyres dealer fitted on oem rims you can tell them you are not happy and expect them to simply fix it.

Some good non dealer service options in Melbourne if you want to avoid the Tri Star tax.