Peel potatoes and with a mandoline or other hand-held slicing device cut length-wise into 1/8-inch-thick slices. Immediately arrange potatoes in one layer on baking sheets and brush with remaining oil.
Bake potatoes in middle of oven until golden, 12 to 15 minutes, and while still warm transfer with a metal spatula to racks. Sprinkle with thyme and salt to taste. Chips may be made 3 days ahead. Cool chips completely and keep in an airtight container at room temperature.
