Tire insurance?

I would worry about 5 year old tires not knowing how they have been cared for during that five years and how many miles. In this case more miles is better as it reduces the dry rot that sets in from sitting still, heat and motion circulate the protective chemicals through the rubber (from Michelin or Goodyear web site).

If you are concerned you might go to a tire shop and have them expected. This would include dismounting them to inspect the interior. This will not be an inexpensive operation, but it is less than replacing a tire along side the road.