Digger

It's a really interesting vehicle shape! What's the reason for the much smaller and thiner tyres at the front? Are the rear wheels where the power to drive the vehicle forward is generated and are the front wheels for steering the vehicle but they just rotate with the motion of the vehicle and don't have any specific mechanism forcing them to turn?

Vinca You are correct. The digger as they are slang termed were the first rail dragsters that were generally front engine with rear drive. My hero Don Garlits was the pioneer of the rear engine rails after he lost part of his foot to a drive failure explosion in a digger. The other advantage they offer is not getting burned from hot oil or injured from flying engine parts when they blow up.
If I dig it out of my archives and scan a few pics I took of Don's Swamp Rat IV digger years ago when it was in my business parking lot so you can see how primitive they were at the time.
Getting to sit in one of Big Daddy's dragsters was the opportunity of a lifetime for one of his biggest fans (me )
What a magical night it was and all because I was paying attention, saw his driver lost looking for a place to park the rig,get some dinner and drink some beer