By portable air compressor, I mean M3. I got in my 328i to drive to my girlfriends this afternoon when I was greeted by a low tire pressure light. It said my left rear was low, and sure it was so low it didn’t even register on my gauge when I checked the tire pressure manually. So went back into my apartment, grabbed the keys to the M3, and filled up the tire and then headed to my girlfriends.
I checked it when I got back to my apartment this evening and it’s back down to 20 psi after being filled to 35 psi. Looks like I’m filling it up and then taking it to discount tire tomorrow. The M3 might get pressed into daily duty tomorrow.