2015 Oak Tree Grand Prix

[1] It was the second consecutive year the event was held as part of the United SportsCar Championship.

The 2015 Oak Tree Grand Prix was the tenth of twelve scheduled sports car races of 2015 by IMSA, and was the seventh round not held as part of the North American Endurance Cup.

Cars in GTD were sent out first before those grouped in GTLM had a separate identically timed session.

Regulations stipulated teams to nominate one qualifying driver, with the fastest laps determining each class starting order.

IMSA would arrange the grid to put all GTLMs ahead of the GTD cars.