Losing air pressure

I put a set of new Michelin tires on a year ago and have only put 800 miles on them. Both front tires continue to slow leak about a pound or two a week. I went back to the tire store and they replaced the valve stem on one. Not sure if it helped. Do I need to seal the rim to the tire with some product or something? Never had this happen on any other cars before. Thanks

Cold weather will drop air pressure. You sure its not from the weather? Air pressure fluctuates.

I would tub tire and look for leak.

Does wheel have clip on weights?

Well I’m in Florida so the weather I don’t think is the problem as up north where the cold temps would come into play. I’m going back in next Tuesday and they will polish and seal the front rims. I’ll know soon enough!
I’ll post the results, thanks guys

Several of my alloy, alum wheels have developed slow leaks. My tire shop, breaks down the tire, cleans the oxidation off the wheel bead area, sometimes puts sealer on and remounts. Owner told me, it is a continuously on going issue.

They usually mark the tire to wheel location and do not rebalance. Since they messed up on this big time and cost me a trip back, I have them check the balance, before it goes back on the vehicle.