Combine oil, vinegar, and garlic with rosemary in a self-sealing bag. Add pork tenderloins and marinate them for 30 minutes in the refrigerator.
Remove from marinade and discard remaining marinade. Season tenderloins with salt and pepper.
Grill over medium-hot fire, turning occasionally, for 15 to 25 minutes, until meat thermometer inserted reads 155 to 160 degrees F. Slice to serve.