5th Wheel location

I refuse to run over 12,000 on steers. I'm OK with 11.6k-11.9k as a matter of fact, empty or loaded (T700 for example) but these roads and bridge approaches are too bad in areas to be riding around with 13k on the steers. I also suspect that steer tire wear will accelerate in proportion to typical steer tire weight. You have to be sure if you suck it up too far that your mud flap hangers don't get tore up turning over other-then-flat roads on the landing gear structure.

But I say this as a company driver who doesn't fret too much over a little MPG loss and who works for a company who doesn't buy into this whole "green, low carbon emission" crap. Sensible driver, sensible speed, sensible tractor aerodynamics, if that doesn't get you into an MPG you can make money with, you need to find another business to run.

 

I don't think that sliding the 5th wheel forward 3-4" alone will increase MPG's .5, there must have been some other variables too. But to answer your question, I don't think an extra 500 lbs. won't hurt the suspension/tires, assuming they are all in good shape and have been PROPERLY maintained. Newer trucks are coming from the factory with 13,500 lb. rated axles for this very reason. Make sure your steer tires are rated for 6750 lbs. You must also remember if you get the right cop you will get a ticket no matter what you do.

 

I see some reefers where the unit is not more then about 18 inches from the back of the cab. I don't know if they are doing this to help MPG or they are doing this in a feeble attempt to "scale their load" but we store our load locks on the back of the cab and I appreciate a little room to access these without dealing with a trailer where deck plate access should be.

 

Moving your fifth wheel a foot (talking 70k-80k load) will change your steers by far more than 500 lbs. More like 1500 lbs at minimum.
That 500 lbs over on the steers should only amount to about 4" on the fifth wheel slider. As bubbanbrenda said, that is the typical distance between being at 12k versus 12.5k
So what I'm/we're trying to say is I doubt that 4" change in gap (talking only 500 lbs over) is even worth it, as far as "aerodynamically" gained mileage compared to all the negatives it brings from being "slightly" illegal on the steers, DOT bear with a case of the crabs, being number 1.

 

Feeble? No sir. Most of the time reefer guys have the gap closed as a measure to save fuel. Peterbilt had a white paper on their website a few years ago that showed their own testing concluded one could save as much as 3% on their fuel economy by minimizing the gap behind the tractor. So most of the time we have it closed up...

 

Agreed but we've seen plenty of posts from new drivers (and there are plenty of them today) who are screwing around with their 5th wheel position in an attempt to lighten their drives instead of adding weight to the trailer thus removing from the drives. Don't give California any more ideas then they already have by advocating for a minimal BBC gap. It may save a bit of fuel, but I'm leaving mine where it's at and still exceeding the target. I do not want to truck in a world full of European style trucks, thank you.

 

Add weight to the trailer? On a sealed load... just exactly how are you going to add any meaningful weight to a trailer?

 

Damage? Seems unlikely, considering coal truck weight limitations in Kentucky. I don't know how one might determine to what pressure to inflate a tire to handle another 250 lbs., but if that includes increasing pressure it seems to me that would accelerate wear/increase the odds of damage to the suspension/steering components.

One day's run seems it would provide insufficient data to substantiate that cause and effect, even if you always make the same "run" of unspecified distance. Maybe you were driving more gently, maybe you had a tailwind.