This is when you Simulate when viewing the Skeletal Mesh, right? If so, this isn’t entirely accurate for simulating how the mesh will behave once you have an animation blueprint applied to it, and play in the editor (at least, in my experience). However! Check what the collision looks like on your base bone. If you’ve let Unreal create the skeleton on import, it’ll just sort of guess what the collision should be on the base bone, and this can cause some issues when interacting with other meshes/landscape when playing.
I crash coursed my way though making vehicles, and asked a lot of questions - but I have to agree, we need a little more information to help. Vehicles flying into oblivion is sort of ‘a thing’ without a bit of work, anyway. I can’t speak to those tutorials, but if you follow the official Epic one https://www.youtube.com/watch?v=9ariPx6M33o you should be on the right path. It’s not Zak Parrish doing the videos, but they’re good. 