An OTS tune, or off-the-shelf tune, is a pre-made file that you can use to modify the settings on your car's computer. These tunes are made by aftermarket companies and can be used to change the way your car drives and feels. They can be used to increase power, improve fuel economy, or change the character of your car. There are also OTS tunes available for different types of cars, so you can find one that's right for your vehicle.