Owners of a new system for grinding up old car and truck tires held a publicdemonstration today. Mel Pins of the state’s waste tire reduction programsays the “crumb-rubber” producing machine in Des Moines is the only one ofits kind in Iowa.Pins says the company, U-T Tires, received about half-a-million dollars instate grants and loans last year to start the ball rolling.Pins says Iowans are doing a great job in recycling old tires.Pins and other Department of Natural Resources officials along with U-T Tireworkers escorted the public through their Des Moines facility today.