If the tracks don't match, then it's a dead end with no likely relevance to the investigation.
Matching same brand of tires is not the same as having proof of identical tread wear of the tire to the cement track evidence.
And whatever happened to the blood sample evidence taken from the Peterson's residence, evidence that was supposed to provide convictable evidence for an arrest warrant?
If they blood was there I expected an arrest by now. Maybe the police have no evidence to convict. Anything less and they really have nothing, just suspicion based on the fact he is Laci's husband.