No one answered so I will,
Small tree’s? pffft, you can smash multiple large tree’s. Just get enough acceleration, (36+) so you don’t keep getting slowed down.
Don’t crush zeds where you want un-smashed gear though. I recommend some good armor on them also. I don’t know if they work ‘as wheels’ probably. I put 5-6 in front of my vehicle. Works great if you want to go get some easy food like near an ant hill. Run over a few dozen. butcher… put meat in the fridge. rinse, repeat, Make it into jerky/dehydrate you have food for a year.
So what is a roller drum? It’s what used to flatten tarmac roads so they are smooth IRL. Yes, those big 7-10 foot tall things will see in the U.S., with 1 HUGE Wheel Drum in front and back. Not sure why they are so small (width wise) 5-6 small ones them in the Cata, they wouldn’t create a smooth surface, because there would always be a small gap next to each other , that would make an upwards crease when you press/smash the tar next to it.
They weight 1600lb’s or something like it, no matter the size. They will make your vehicle acceleration and top end SLOW, but worth it. Even with a 2-3 V12’s top speed won’t be more than like 600, safe around 90-120.