Mostly spare tires carried on the back of vehicles. We discourage them as much as possible. I once saw a brown male ripe the spare tire off a vehicle with one hand. He took it off the rim in a blink of an eye. I really respected the bears strength after that incident.
Bears also enjoy water.
The brown bears were the most frequent visitors to the two ponds inside their exhibit. They would wrestle with each other or just splash around, and they reminded me of children in a wading pool. The ponds were their hiding spot for items that they had taken from vehicles. They are curious creatures, everything that came into the area was fair game. Visitors were always warned.