The driver's side front tire on my 2019 Kia Forte FE with 16500 miles on it keeps loosing air. I took it to NTB and they pulled out a nail and patched it. The next day, the pressure went down from 32 psi to 20 psi. I took it back to NTB and they kept the car for a whole day. They couldn't figure out what was wrong. They dunked it in water and couldn't find any leaks. They checked the seal to the rim and it was fine. Any idea what is happening? I hope I don't have to replace the tire.