what rpms does your class c run...450-or e350 chassis..?
I have found that they seem to be geared lower than the A's for some reason
coming back croos country, I noticed that the dynamax was rinning at 3000 rpms at 70 mph... it still has the little 225-75-16's on it ...
I think it way over revs and doesn't get good use of the 5 speed...
when I take off from a light it is already in 3rd befoe I cross the street...
that has to kill the MPG...
best I got was 8 mpg running on flat at 70-75
but the rpms were around 3000....
I always change out the tires to 235-85-16's they carry more weight, ride smoother.. and lift the coach about 1.5 inches... they slow down the rpms
speedo ends up at 65mph... reads 60 mph...so the rpms also drop about 400
they pull the hills better in 4th and not over reving so much