Get your whole yard sprayed, too. It does make a difference if you do it a few times. As other commenters here, and I, can attest, it just isn't worth getting a bite. Lyme is awful.
Problem with this is Permethrin is quite a broad-spectrum insecticide and won't kill just ticks but also a lot of other insects (which take care of e.g. pollination and in turn are food for others, etc, the usual picture) and is also not exactly friendly for aquatic life. Also mammals are not completely out of the danger zone, depending on dose. And longer term effects are as far as I know simply unknown. So it needs at least some careful consideration in my opinion.