The floor sits above the tires. I know this for sure when I was walking around the backhoe loader on Monday this week. I was curious about that. But maybe the part that sits above the tires is where the side consoles are covering and they might sit slightly higher than the floor.
There is a few inches air gap. I think that was shown in my reference photos and videos posted.
As far as the uneven part: Are you using a mirror modifier and is your object origin centered with the world origin?
