Preheat the grill to medium heat, about 375°F to 400°F
Scrub the potatoes clean and pat them dry
Pierce each potato several times with a fork
Rub the potatoes with oil
Sprinkle with salt if desired
Wrap each potato tightly in aluminum foil
Place the wrapped potatoes on the grill grates
Close the lid
Grill for 45 to 60 minutes, turning occasionally
Check doneness by piercing with a fork
Remove from the grill
Unwrap carefully and serve