Long story short, Got a flat tire while driving, tried to make it to the shop before it went completely flat. Ended up driving at freeway speeds for a mile with the driver front tire almost completely flat. I stopped before any damage was done to the tire. Probably should have stopped when I noticed the leak. Anyway, pulled over and put the spare on. Slowly crawled back home. Took tire off, got it fixed. Now there seems to be a noise coming from what I assume is the front differential and gets louder with an increase in speed or acceleration. If I get up to speed and let off the gas, the noise goes away. This is on a 2006 Forester X with the auto tranny. I have changed the front differential fluid, which is separate from the transmission fluid and that helped slightly. Is the front differential muffed or is it something else?