weird landing gear animation

Ok, I've been trained for 3ds max and gmax in college. But this is something totally new thats gone wrong. Since im still pretty new to designing, maybe you all can help. I am building a full sized Northstar (an R/C favorite of mine). I have the basic plane done. Im working on making the landing gear and its animations. When i try to animate the gear, the tire warps into an oval and doesnt stay circular. by the time I have the gear retracted it looks like i got an incredibly weird flat tire. When i put the gear back down it returns to normal. Any help, im stumped.