Requested Link: Tire inflation: MPG versus comfort

[plyonsMC9]

We have a request to re-post this topic re:  Tire inflation: MPG versus comfort

Here it is!

https://www.busconversionmagazine.com/forum/index.php?topic=11710.0

Hope this helps, Phil

[Utahclaimjumper]

Why would anyone post a thread that has been beat to death from 2009..>>>Dan

[TomC]

There is only one true way of finding out what inflation you tires should be. Weigh the bus by axle on a Cat scale at your local truck stop when the bus is fully loaded. Then obtain the tire inflation table for your exact tires and tire size. Inflate to what is suggested during winter. Run 5psi higher in hot weather. No other way is accurate. Good Luck, TomC

[luvrbus]

One has to pick a happy spot for himself on tire pressure axle weight is not always the best most converted buses are heavier on one wheel or the other, I have watched converters weighing each wheel and if they get the weight with in 500 to a 1000 lbs they call it good,Best to add air pressures to compensate for the heavier wheel weight I was told,Prevost converters add pressure to the manufacture's tire specs.My Country Coach uses 130 PSI on the 315/80/22.5 on the front tires and that is max rating and I don't see any difference in tire wear or wandering and the rear and tags are 105 psi only difference I see is a rough ride on the front axles with the IFS @ 130 PSI.I am pondering the idea if I have the clarence of using 365's on the steering like Prevost for less psi and a better ride   
     

[TomC]

315/80-22.5 are rated for 75mph, but only at 18,000lb. 20,000lb is 55mph. I would seriously consider going with bigger tires in front.

[luvrbus]

315/80-22.5 are rated for 75mph, but only at 18,000lb. 20,000lb is 55mph. I would seriously consider going with bigger tires in front.

I am heavy my GCWR is 67,000 lbs that is only16,000 lbs less than a 18 wheel truck and trailer,my weight is around 50 to 51 thousand lbs.the ISX does a good job with pushing and pulling the weight to I can average 7.5 mpg every day @ 70 MPH,I do worry about blowing a tire on steers though 

[buswarrior]

The 365 on the front sure do like to wander around, following whatever imperfection is out there.

What is your steer axle weighing now?

Happy coaching!
Buswarrior

[luvrbus]

The 365 on the front sure do like to wander around, following whatever imperfection is out there.

What is your steer axle weighing now?

Happy coaching!
Buswarrior

17,800 lbs

[buswarrior]

17,800 lbs

That is obscene! It actually weighs that on the scales?

An entire GM 5307 weighed 23k empty...

Happy coaching!
Buswarrior

[Van]

17,800 lbs

Wow! Thats the  Equivalent of 712,000 oreo cookies! Your coach needs a diet Clifford!

[luvrbus]

That is obscene! It actually weighs that on the scales?

An entire GM 5307 weighed 23k empty...

Happy coaching!
Buswarrior

Yep it has a 18,000 lb rating .I have a 18ft slide on the passenger's side and 14ft slide on the drivers side and both have some heavy duty framing plus the 12.5 generator is ahead of the steers in a hush box it is heavy.

[windtrader]

Given the painful bill at the fuiel pump, I decided to up the pressure all around on my bus.
It weighs in around 32k, I think about 12 on the steers 20 in the back.  I just put 100 all around, well withing spec.
The ride is firmer, not harsh, nothing is really hard riding on air. As to improved MPG that will take a few tanks to figure out because much of my travels are up and down so hard to get a good average reading.
I am inclinded to go back to the more accurate lower settings if the increased comfort is "worth it"?

As to steering, no difference in wandering or feel, drives the same at both pressures.

interesting of note: couple weeks ago, i drove car from Sacramento, elevation 50 up to Tahoe, over 7500 at pass. got about 32mpg on that leg. On the trip back, there is a big sign warning about downlill grades for the next FORTY miles. Got about 45mpg on that leg. lol

[dtcerrato]

Higher tire pressure for the average drive, ie: smooth asphalt is hardly noticable but do the extreme as in the far NW corner where pot holes, frost heaves, & wash boarding is common - dropping to the proper load rated pressure is like night & day both for comfort & handling. Oh & good shocks make a big difference in the same condition differential.

[chessie4905]

Good luck seeing ACTUAL mpg improvement. Driving 5 mph slower would yield better results for most except Clifford and others with lots of overdrive.

[RJ]

Given the painful bill at the fuel pump, I decided to up the pressure all around on my bus.
It weighs in around 32k, I think about 12 on the steers 20 in the back.  I just put 100 all around, well within spec.

Don -

I'm going to speculate that you're not going to see any difference in your fuel mileage, or at the most, decimal points different.

As has been pointed out earlier, just take your bus to a truck scale in full, ready-to-roll condition, pay the $15 and get the weights on each axle, instead of guessing. Then set your tire pressures to the load/inflation table for your tire size and manufacturer. Just do it right and you, mama and the bus will all be happy campers.

FWIW & HTH. . . 

RJ