Question about axle ratios

Got to be for off road. The lowest gear ratio in a road truck I drove, was a 4:44, with a 13 speed, it was a 62 mph truck. Back when the speed limit was 55, that could actually get you in trouble.

 

Used to run some late 80's AutoCar roll off trucks with 5.29 gears. They were big Rockwells larger than the SSHD,s? A rebuilder told me they were designed for portable drilling rigs and he had never seen one before.
The transmissions were RTO14607LL? Definitely a deep reduction 7 spd with about 25% OD. One of the worst shift patterns ever.
You could put it in deep reduction and crawl out of a slop hole heavy. On the high end thy would cruise at 65 with no problem. If you dropped off a hill loaded in a gear to high that worked out to about 80 MPH @ 2500 RPM.
One of the big cans was left on a truck, maybe over a holiday weekend and it rained the entire time. It was loaded with paper pulp and hit the portables @ 92,000 Lbs on three axles.
I was told the AutoCar did not care much but Barney was very upset.
Specing is a package deal. All the parts have to work together but these worked very well.

 

You need to lay out what you are looking at and what you want to do with it?
A lot of trucks with those ratios had pad mount suspensions. Would you or your driver be OK with that on rough Interstate slabs?

 

You are going to find yourself burning fuel at 5.xx god only knows what back there.

I had a El Camino with a higher rear end on the order of 4.05 or something or other. Topped out at 80 at redline on that V8 of it. But loaded with a thousand pounds of stone out of the ready mix? (Beyond limits) no problem.

 

You need a second axle under there. You will be very surprised at how much those single axle tractors hate to be loaded.