well, not real sure on the nitro bit but i know we run the tc4 on dirt and run green springs on rear and about 4 weight not much to do to get it up just kinda let it drag be cause then you loose rear softness if to far in air...usually look for around the space of a spur gear to slid under neath as a good rule of thumb and try to run a tall tire like the perelli or other HPI or the associated rally. on the front of tc4 we use silver or blues with latemodel bodies about a 4" side damn and 2" spoiler.
hope this helps get u in the right direction