I count eleven in the one picture, and I don't think that's even all of 'em. Eek!
Probably don't need *that* many, but it might be nice to use a few around the door. And if they weren't horribly hard to do, a few scattered around would be nice. But I dunno. Seems like rubber would be really hard to cut, so maybe it's not really practical.
Do you have to cut 'em?
How 'bout if you made a square- 3 tires by 3 tires - plant inside the square also inside each tire.