Tires are a tough call due to shipping cost having to be an added factor for anyone living outside of your area. So adding that as a factor makes a local sale much more enticing than a shipped sale to another state.
I have sold barely used tires before and found that I got the most selling to someone locally.
Ask twice for what you want for them which you deem fair and then if you don't get your asking then lower it to your "lowest price" that you are willing to sell them for. Most people will ask for your lowest price/best in PM's or in this thread anyways
I would take 30% off since that was what I started out with and sold a set of Michelins in the 20" Sport wheels staggered configuration within the first 24 hours to a local. Even hooked him up on the install since the tire place is a shop I frequent.
GLWS