When approaching large rocks, choose a path which ensures you drive over the largest with your tires. This will lift your undercarriage over the obstacle. The tread of the tire is tougher and thicker than the side wall and is designed to take the abuse. Always look ahead and make every effort to cross the large rocks with your tires.
Never attempt to straddle a rock that is large enough to strike your axles or undercarriage.
Never attempt to drive over a rock which is large enough to contact the door sills.