State and local officials gathered in Vinton today to mark the clean-up of a half-million used tires. Iowa Department of Natural Resources environmental specialist Mel Pins says the tire pile-up started in 1990, when the “Rosebar” business opened in Vinton.The state paid a Des Moines business to grind the tires.Pins says the tires were shredded for a number of uses.Pins says huge piles of tires are a health and safety hazard — as tires are a breeding ground for mosquitoes — and it’s hard to douse a fire if one starts in a junk tire pile.