2006 Toyota Matrix tires problems

Jan. 2007 anchorage, ak driving 50MPH on a highway, as the road bended to the right, we went into the turn and began to slide sideways. It was 30 degrees f, so we must have hit black ice. I tried to correct and sent the car fish tailing to the other side. We whipped back and forth a few times, before the car started to spin. We did two full circles before we gently hit a burm of snow and came to a stop. No other cars were oncoming so we did not have any significant damage and there were no injuries.

Purchased certified pre owned - (leased) 2006 matrix 27940 miles 7/26/08 - on 11/12/08 32955 miles after oil change dealer wrote : "tires are wearing funny - aligned at n/c did not rotate rht rear cupping - 3/25/09 oil change 38632 - dealer wrote - rotate tires if needed - last time in had tire wear issue needs tires has 1 good tire on car on lf. Apparently this is a problem with toyota - haven't contacted dealer yet but will after reading complaints.