Man, you don't need them. I cut mine off and didnt put new ones on, & I didn't know there was a small open space there until now.
if it's -34 here and I can't tell the difference, you can probably do without. I find all mine did was just create a space to collect snow and road salt, which I can easily remove now if it builds up. The rigidity isn't affected that much, mine are solid. I just think if you want to save $50, you may as well lol