Looks like we are highjacking another thread, but I am also interested in slow tire pressure loss. I have one tire that loses about 4 psi in 2 - 3 weeks - enough to be bothersome, but not enough to easily find the cause. I had 4 new run flats installed about 9 months ago and did not notice the problem until about 3 months after installation - then the start of the pressure loss. Had the dealer check and could not find the problem, but they re-torqued the sensor-valve stem. Any ideas? ...bad sensor, ...O-ring, ...rim, ...tire???

Looks like we are highjacking another thread, but I am also interested in slow tire pressure loss. I have one tire that loses about 4 psi in 2 - 3 weeks - enough to be bothersome, but not enough to easily find the cause. I had 4 new run flats installed about 9 months ago and did not notice the problem until about 3 months after installation - then the start of the pressure loss. Had the dealer check and could not find the problem, but they re-torqued the sensor-valve stem. Any ideas? ...bad sensor, ...O-ring, ...rim, ...tire???
I moved this post over to the tire and wheel area so others can find it.

I suggest you take the car over to Discount Tire (one of our site sponsors) and let them test for leakage. If it isn't the TPM's or the "O" ring seals then as a suggestion I would have them put nitrogen in the tires. It really works for many slow leak issues.

Keep a record of the tire pressure and see if it is corrected. If not then we'll have to look at other options.

Pleae keep us informed

Looks like we are highjacking another thread, but I am also interested in slow tire pressure loss. I have one tire that loses about 4 psi in 2 - 3 weeks - enough to be bothersome, but not enough to easily find the cause. I had 4 new run flats installed about 9 months ago and did not notice the problem until about 3 months after installation - then the start of the pressure loss. Had the dealer check and could not find the problem, but they re-torqued the sensor-valve stem. Any ideas? ...bad sensor, ...O-ring, ...rim, ...tire???

In my experience, the most common (and by common I mean it is also frequent) cause of slow pressure loss with alloys is poor seal between the tire and the rim. This seems to affect all alloys sooner or later and is absolutely typical after a tire change. It is solved by using a rubber glue/sealant between the tire and the rim. In theory careful cleaning of the inside of the rim will prevent the problem but from my experience it doesn't. The thin sealant/glue has no effect on performance and does not cause any problems when replacing the tire either. I don't know why it isn't done as standard practise.

Occasionally a faulty valve is the problem but that is much less common assuming a new one was fitted with the tire. (This doesn't apply to TPM systems.)