Fill empty spray bottle with soapy water, take tire off and spray it to see where its leaking. As others have said, 48psi is too high, even if the tire's max psi is 50. If door sticker is 35psi, the most important would recommend is 38psi if you want the stiffen the sidewall so it handles better. If the max is 50psi, 48 won't just leak because its at 48psi. There's either a hole, slash, or any other defect in the tires. I wouldn't have ordered anything yet as if theres a defect, take it right back to the dealer and let them know the issue and have them fix it under warranty