Wheeled vehicle physics problem

Hi, this is my first post here and I don’t speak english , so I hope I’m not making mistakes.

I’m making a game where the player can drive a rover (like NASA’s curiosity) on Mars. I followed the official tutorials on youtube and watched a lot of videos about this. Everithing works fine until the rover reaches a certain speed, then wheels start “bouncing” like they would do with a very irregular ground, even if the ground is flat. Almost all vehicle setup options have default values. I had to set max RPM to 800 because is the maximum one that does not reach that speed at which the rover start having this issue. Does someone have any idea of what’s going on? Can someone, please, help me?

thank you for your time