A lot of Losi tires have tread on the inside of the tire. I've never known the scientific reason for this, however, I've always thought of it as tread for the foam. The rubber can grip the foam better, but then again, I don't know how this would help. Lately, I've been using spray glue to glue the foam to the rim. It makes the tire more consistant in roll and traction wise.
That's my input.
TQ Racing Wire