I'm sure I recall an incident my friend had correctly with potholes, she tried to claim off the council for the buckled wheel but the council said they couldn't reimburse for the cost of the alloy because they didn't 'know' about the pothole. Further to this they stated that they could only reimburse people for potholes that have been recorded and that they know about.
One of my mates works for local highways and says this is corrrect, if they don't know they are not liable. Best thing to do is to report every pothole you see and keep a record of the call. However if you hit one that has been highlighted, usually painted around it, they have 7 days to fix it, you should be pretty much guaranteed a payout.