I have had good luck with the plastic square ones.I am assuming that they will flex a bit and maybe eliminate cutting the track if the stud is under alot of stress.When I had to use round I rounded off all edges before installing.Just My opinion and past luck running 12000 miles with out losing any.I also stud on the outside.Also a great amount of common sense as to what a person is spinning on will dertermine how long they will stay in.