Several environmental and community groups filed suit in Modesto Superior Court to stop the world's largest pile of used tires--an estimated 42 million of them--from growing any bigger. The suit seeks an injunction to bar owner Ed Filbin from adding 20,000 tires a day to the huge pile near Westley in western Stanislaus County. Filbin has been collecting tires for 20 years. The legal action contends that the pile poses a serious environmental and fire threat. A commercial plant that burns tires to produce electricity is expected to go on line at the site by month's end.