Ive had the same tires on since i bought my is300 and have gone ten thousand miles. Just the other day i was at a stop light and the guy next to me told me that sparks were coming out right on the inside of both my front tires. When i got home i looked and both of my front tires are completely worn to the threads on the inside of both tires. Im not really sure what would cause this because my rear tires have about fifty percent tread left but the fronts are just worn out. I dont know what would cause the sparks so any help would be appreciated.