paradigmgt

My wife has a 2009 C300 with the multi spoke wheels as pictured. Each wheel will randomly lose air. Is this normal for these wheels? Are there known valve stem issues with them? What about changing over to W205 17" wheels - are there any fitment issues there?

Accidental L8 apex

The aluminum is probably corroding on the inside where the tire bead sits. Having the insides redone would be cheapest.

BlackML550

Tyres from brand to brand all have marginally different tolerances. Mine were similar (2 of 4) with very slow leaks over most ot their lifetime. When I changed all 4 to a different brand but same size, the problem disappeared.

Just204

I typically have no issues, take a bottle with dish soap in it and spray the valve stem, the core and around it. Leave it for a few minutes and if it bubbles that’s your leak. If it’s the outside part of the stem there’s a trick to fix it but a shop needs to do it. If nothing check for nails carefully, if none then most likely the inside bead is leaking. Tire needs to be broken down and rim need to be cleaned if there’s corrosion (which I never have an issue with on OEM MB rims), maybe add bead sealer. Are you in NY?

TimC300

Since I got my W204 it seemed I was always filling the tires with air monthly. It was every tire constantly, not just a random tire.

Try torquing down the nuts on the valve stems. 11mm deep socket at 8nm/ 70 inlbs. Don't even have to take the cap off. That seemed to work and the tires seem to hold air much better, haven't filled them all winter so far. I also recently bought a valve core torque tool and tightened the cores up a bit. If the gasket is old and leaking then if they are the Mercedes sensors the Schrader 20013 rebuilt kit will fit, but requires removing the sensor.