2010 buick lacrosse cxs the other evening as i was driving home with my wife a little before sunset at about 30 mph i heard a thump and assumed i had hit something. neither my wife or i had seen anything in the street. i continued to drive home (3 blocks) and the car drove normally - no change. when i got home i examined the front of the car (drivers side) and saw nothing unusual but noticed the back right tire was flat. i got out the jack and changed to the spare. upon looking at the tire i found no apparent damage to the tire other than it was obvious i was driving with the tire flat. upon closer examination of the wheel itself i found a gash in the wheel about 6" long and elevated up into the tire area over an inch. of course all of the air escaped through the gash - no blowout. went to the dealer (3800 miles on the cxs) and they determined i had hit something in the street - no warranty coverage. cost for new wheel and tire - $1002.00 went back to examine the road (no potholes) and finally found a rock off the side of the road that apparently caused the problem. it was a rock, flat on both sides about 2 1/2" thick and about the size of a red brick only oblong. have no idea how it hit the back tire and not the front. i am convinced that had the tire been an older 15" or 16" tire the tire would of absorbed the hit and not damaged the wheel. of course it may have blown a tire but the wheel would of been in good shape. with the roads becoming so bumpy with potholes i now worry about hitting a bad spot in the road and having the same thing happen again. i carry a $1000 deductible insurance so insurance will not be involved. (in 50 years of driving i have not had an accident that was my fault or any other damage to one of my cars - so i carry a high deductible). just a word of warning to ...