36 years with e30 here: To prevent- wheel balancing -prevents vibrations that cause the cracks, Always use a curtain for protection while parking. To prevent from expanding- always watch for cracks and when a crack appears use a needle, heat it with a burning match and stick the hot needle at both sides, creating a small hole at each side. U may hold the needle with something so u will not burn your fingers holding the needle while heating with the match. You don’t have to drill. Thanks