iRV2 Forums - Pumping up tires

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Quote:

Originally Posted by RVNeophytes2 (Post 1559215)

Steve, we are a global bunch: I'm penning you a quick note from Tokyo, wee hours.
:greetings10:

'Glad you found the carefully concealed blue-capped hookup, suggest using two hands and safety glasses; that thing is going to cost someone an eye, one day.

My weights are nearly identical to yours. 'Got XZE Michelins on the steers and soon-to-be-replaced Goodyears on the drive/tag. The book called for 115 up front, about 105 in the drives, and less than 95 on the tag.

Just the other day, I opted to put extra in the rear to see if the ride and mileage improve. To stay organized mentally, I descended in pressure from 115 up front, 110 in the drives, 100 on the tag. No change in ride, nominal change in the contact patch where it matters least, and (initially) a whopping 20% rise in mileage.

This comes on the heels of being the laughing stock of our circle of 500-ish hp rig owners when it comes to diesel consumption. I mean, my buddies are driving like demons compared to my grandma pace, kicking my arse at the pump. The one constant I noticed is that my inflation values aft of the steers are much lower than theirs. Even the tire shop guys remarked that the pressures seemed low, but I doggedly adhered to the Michelin tables.

If my theory is correct, I'll have good traction, safe summer running temps, smooth ride, and be a rock star at the fueling island. Let the test begin...

Very interesting,
So you are suggesting increasing drive and tag pressures have improved mileage.
I've been interested in the mileage more as an experiment.
I agree with Mike Canter that all things being equal 1 mile per hr = .1 mpg
So I aim for 62-63 mph - at that speed you pretty much get to smell the roses.
So I'm averaging 5.3 mpg been down in the low 4's at times but happy at 5.3
Because I've been in the high country and about to head down hill after Raton Pass back to Dallas I probably wouldn't get a true indication of improvement at this stage.
I will however go to 110 and 100 drive tag for the next trip and see what happens . I'm running 315's on the steer so 105-110 is probably the right money for the weight
PS
We love Japan, wife loves Tokyo,
We ski in the alps and up in Hokkaido regularly

Interesting, guess I will have to try a trip with increased tire pressures on the drive and tag axles. Steve if you try it then let me know what happens.

You are 100% correct on the dangers when disconnecting the air hose. It can fly. I have had it pop off right after I connected it also and hit me in the chest.

Quote:

Originally Posted by Mike Canter (Post 1559623)

I had trouble getting the female fitting on in the first place.
I felt from the pressure required to insert it that I'd need to be careful detaching it.
So I was careful.
I'm pretty sure Michelin sell the Energy tires based on their rolling moment, if that's the right word.
My next trip is mid July so ill experiment then.
Might arrive at your place on the way back down the map.

Steve, I'm heavier than you by a bit - must be the huge tool box and spare parts. I'm running 110# in my 315's up front and 105# drive axle with 100# in the tag. It's worked well for me for the last two years. I do travel at the speed limit since we have to get there and it is not about smelling the roses along the way.

With pressures above 100#, the on-board air system takes a little patience when filling the tires. The air system needs to cycle a few time to build up pressure, especially when airing up the front tires. I had plenty of room in the basement storage bay just froward of the wet bay so I bought a small compressor and keep it plugged in, hose attached, and just a flip of the switch away from being ready for use. It builds up pressure to 150# quickly and I can adjust my air pressures easily without running the big Cummins.

Husky 4-Gal. Wheeled Stack Tank Compressor-H1504ST2 at The Home Depot

If you have room, you may want to consider something similar.

Quote:

Originally Posted by Les Stallings (Post 1560145)

Hi Les
I've just found my blue knob
Give me a chance to play with that before I discard it for better things.

I would suggest that if you are going to use that air in the propane bay that you put a shut off ahead of the quick connect. With all the road dirt that collects there it's a good spot to acquire a leak.

I'm with Les.. have always had an on board, makes less noise in campgrounds, air to inflate stuff, blow out compartments, etc. A 400HP air compressor just never made much sense :) :)

Quote:

Originally Posted by Twomed (Post 1560248)

I'm with Les.. have always had an on board, makes less noise in campgrounds, air to inflate stuff, blow out compartments, etc. A 400HP air compressor just never made much sense :) :)

x 3

The air fitting on Steve's and my Signature is not in an open bay such as the propane bay. Our bays are sealed and actually mine has a TV in it. It would be a good idea to put a shutoff valve before the end. It would make it safer and easier to connect.and disconnect

Steve, the connection in the back is probably an inlet so a tow drive can air up and release the brakes.

I know you found your outlet but want to add that mine is in the generator compartment up front on the passenger side. 08 HR Endeavor. There are two connections there. One for adding air to the front tank and one for stealing air. On the outlet one there is an on/off valve.

One more note on the rear connection. There may be a check vavle so in case of a leak you would not lose rear air.

Apparently my draw bar is "extra heavy duty"

But I can see it is only stamped for 10000 lb
At some stage the previous owner must have had an airforce 1 system.
If it were a full air system there would be both a male and female connection