Gore and I believe recent belt tears are the result of cocked adjusters. Never, ever use a fiberglass seat. Pull the belts tight every time there's a yellow flag. Tension springs on the adjusters help keep the belts tight. The crotch strap prevents the lap belt from riding up.
Some lap belts come with a Velcro-equipped tab that prevents accidental opening of the latch.
If you ever once accidentally open the latch of your belts by catching it on your driving uniform, gloves or anything else, change the latch configuration before you run another lap. Installing a new lap belt with a latch guard is a good idea, especially for those who might open the latch accidentally. The lap belt's adjuster should not ever be able to contact the opening in the seat through which the belt passes. Gore's research has found that a 10-inch length of webbing is perfectly capable of stretching over two inches, much like a big rubber band. If you install your belts such that their adjusters are outside the seat, and we recommend against doing that, provide sufficient room for the belt to stretch without the adjusters contacting any part of the seat's openings.