Fluctuation in MPG

[Broompilot]

Had a load from Detroit/Denver 9500lbs all flat until Western KS mileage was dissipointing to say the least.

Just put new Steers on (first problem)
Weight balanced like a Pro (even passed CO scale house)
Fuel the same Pilot/& J.
No wind beautiful weather little rain in IN.

Fuel was about 20% below previous tank, only improved about 10% with half that weight back to D.C.

Took the truck in when I got back home had the tires highspeed balanced on the truck. Should have seen it shaking even the rears touching the ground I could put my hand on the rear tires while the fronts were spinning and could feel that shake until they put the correct weights on it.

I also had the tires Trued again (steers) I had this done months ago but had a belt fail in one of my steers all though it was not causing me any problems yet I do not trust bad steers.

So my question is how much difference do you see between loads?

Prior to replacing the steers averaging 10.3 to 9.5 8.8 heavy load with poor road conditions.

After installing new tires 9.2 best all the way to 7.7 that hurt.

 

[davekc]

Air pressure would be the first place to look after all fuel concerns are addressed. Is the tire tread different? Keep in mind that a air leak from your after cooler will drop the milage as well. Air and fuel filter ok?
Vibration could be different issues. Everything from worn bearings, king pins, tie rods to a simple alignment. A suspension test and alignment should isolate the problem. Suspension machines are available at most KW dealers.
Test is roughly $200.00 depending on the dealer with the cost applied to any repairs.
Several items to consider.
Process of elimination for sure.
Let us know how it goes

Davekc

 

[LDB]

I read somewhere the difference between a brand new tire and a tire that was 50% used up was something like 7% which seemed like a lot to me. That would drop 10mpg down to 9.3mpg if it's true. I've also heard not to expect best mpg until tires have 50k miles on them. I can't swear to either one but I do believe you'll see a recordable reduction in mpg with new tires. I'd guess you'll see an improvement after 10-15k miles.

Leo Bricker
OOIDA 677319
truck 4958
73's K5LDB
Support the entire Constitution, not just the parts you like.

 

[Broompilot]

Front end is in very good if not perfect condition, balance and toe are perfect. Air pressure was 110 as recommended on the side wall (I put in 115 during this procedure just in Steers) as I had done on my previous tires.

I truley believe the difference was all that shaking from having them balanced at the install instead of taking it to a front end spcialist that balances them right on the truck. All that shaking has got to kill performance. If you have never had this done try it you will be amazed. The tire if you kept your eye on as it slowed to about 30mph you could actually see the high side and low side as it spun going up and down with every rotation and I mean almost a quarter of an inch in between high and low. The rims have been measured and are perfect. Tire mfgs believe they make a perfect product when it really needs fine tunning right off of the floor.
And Tire dealers really know nothing except how to install and sell them, a front end specialist will tell you as they did me it is not the bad roads that tears our front ends up its the out of round tires shaking the crap on each rotation at 60mph that wears those King Pins and Tie rods apart over time. Not noticable to a driver until he has a great front end tire balance done. (at least me)

After pulling out and driving back home the improvement in smoothness is unbelievable. I would not believe this could be possible if I did not expierence it myself. Find it hard to believe that two tires can and do make such a big difference but this is now my second time and both expierences are the same, smooth as silk.

 

[davekc]

While not all tire dealers perform this service, it can make a huge difference. As mentioned, a large percentage of tires are out of round when they are brand new.
Balancing will not correct the defect.
These machines that they use are expensive as they cut the tire, but it is worth every penny for the service when installing new tires.

Davekc

 

[guest]

Centramatics. At $150 to $200 they are cheap insurance against the front end trouble lots of people have in straight trucks, though they won't help an out of round tire.

I recently got new steers and put Centramatics on.

Balance Masters do the same thing and probably do it better than the Centramatics.