I am not sure what the appropriate forum is for this question; I posted here since I am getting a 2017 Super Duty and am asking this question with this in mind.

(pertaining to dual rear wheel trucks)

I was driving down the highway yesterday and was behind a bucket truck. I noticed that its front wheels were in line with the outer rear wheels. It pulled off a ramp before I could catch up with it and see what type of truck it was.

Later on that trip I passed a landscape truck loaded down with mulch. Its front wheels were in line with the gap between the rear wheels. As I passed, I saw that this truck was a recent model of Dodge Ram 5500.

When I was shopping Ford Super Duty trucks, and was considering a F-350 dual rear wheel, I thought I recall that front wheels were in line with the inner rear wheels.

What are the considerations for the front wheel alignment with the rear wheels? (such as why would a bucket truck want the front wheels aligned with the outer rear wheels)

or is there any... also while driving on the highway I didn't have the opportunity to jump out and measure the axle lengths, I assume that has just as much importance in the reason for the alignment. To simplify this question, assume the same rear axle characteristics on an imaginary truck, and the only thing that varies is the length of the front axle to accommodate the placement of the front wheels to have the alignment in question.

 

It is going to vary a little bit. My 350 dually has the front and rear inner wheels generally inline with each other. The F-450 has a wider front axle...so its front wheel will be somewhere in between. It really doesn't matter. The wider the front, presumably the sharper the truck can turn. Some people like the wheels to align for better tracking in snow or ruts. I don't seem to have much of an issue.

 

I suppose I was thinking there was some sort of functionality the manufacturers decide on. Like the bucket truck, having the front wheels in line with the outer rear wheels, possibly it gives the vehicle more stability when the bucket is extended?

 

The bucket truck is just a chassis purchased from the manufacturer who has no idea what the use will be. So the wider track might be beneficial, but that would not be the manufacturers' intent. Most bucket trucks of any significant lift height have their own hydraulic stabilizers that fold down anyway.

 

They could have installed deeper offset rims, or even added spacers to the front wheels to offset them. Possibly a stability thing for the bucket.

 

Pick ups have wider rear frames so the duals have to stick out further in order to clear than on a chassis cab. 450's and 550's, as well as most mdt's and all hdt's have wider front axles so the front tires stick out more. Pretty much anything that isn't based in some way on a pick up will have the steers more or less lined up with the outer duals, assuming the same size tires front and back.