I would recommend the universal offset brackets. If you do not have oversized tires and factory flapres the 12" offset bracket should be enough for you.
If the tires stick out passed the wheel well you will want to go with the 14" flaps and offset brackets. If the tires do not extend passed the wheel well you will be just fine with the 12" wide offset brackets and full style 12" wide flaps
For this you would need to go with the 14" flaps and brackets. This will give you an offset so the tires do not rub on the flap and it will also give you protection outside the wheel well.
The brackets will install on the lip of the fender with self tapping screws and you will be able to take the 18" long flaps and trim them to the desired length.
The brackets are a universal bracket. The size difference is the distance the bracket will move the flap away from the wheel well.
Most oversized tires will be ok with 1" the 1.5" is best with very large tires. The measurement is taken at the bottom of the fender where the wheel well starts and measure away from the tire.