[bigjae1976]

If its a slow leak, usually its from the rim bead or valve stem.

I'd just spray some water on the valve stem and see if it bubbles.

If there is no issue, its probably from the rim bead. Sometimes, there is some defect on the rim or tire that makes it more prone to a small leak. Then, sometimes, the bead won't leak unless the tire is rolling or under load.

So the dealer may be correct.

When I used to mount tires many years ago, I'd put some bead sealer under the rim bead and it would be good to go. Not ideal. If you are very anal retentive, you can try a new tire and then try a new rim.

BTW, let me know if you want to swap your rear rims for a set of OEM 18" front wheels. I have a pair of mint front wheels.