RAF will tell you something about your grandmother's toffies and ask you to stop wasting their time.
The local municipality's road maintenance dept, relevant to where the incident happened, needs to be held accountable, or if it's a highway, the JRA is responsible - but you need you need to jump through all manner fo circus hoops to make it happen.
Go to the pothole and take pictures of it from every conceivable angle... both up close, as well as wider angle shots including some landmarks if possible. Measure the depth and diameter of the pothole.
Get the street name and address if it was in an urban area - otherwise, GPS coordinates and relevant details for the closest intersections, so they have no excuse of "we couldn't find the pothole"
Take pictures of the damaged rims and tyres, and take them somewhere reputable to generate a quote for replacement repair.
Take all of these details, and attach it in an email + a hardcopy letter, both to be submitted to the correct department and person, along with your bank account details and your particulars.
Then starts the following up - 3-6 months to get them to pay out, and that's if you lean on them.
And another tip - ALWAYS specify expensive aftermarket wheels on your insurance policy, otherwise you're going to come short if trying to process something like this through insurance.
Good luck.