I have the same problem with my pantiger since it use Tiger I hull. I'm 99% sure it's because too many tracks. I have not yet removed a link or two yet though. I thought about slow turns but it's hard to achieved it with Heng Long 2.4GHz. Neutral turn when turning helps a little bit though. I didn't test this extensively unfortunately. I have metal idler wheel & tracks. Too much play in the idler wheel is a possibility too. I did researched a little bit on how to fixed this. Track tensioner & metal bar to stop hull flexing always come up in my search.

@Marc780, do you have picture how to install the ball bearings in the idler wheels?