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10-19-2008, 12:34 PM #1
How to air up the rear inner tires on a dually?
My friend asked me to find the answer to this question since he just bought a new (to him) dually truck.
There doesn't seem to be anyway to reach the stems on the inner tires.
How do the pros do this?
10-19-2008, 12:38 PM #2
On my 2007 Dodge dually the fill stem for the inner tires is extended and you can easily reach it via one of the open spaces in the outer tire wheel. The outer tire stem faces "backwards" so you do need a two sided air fill device and/or pressure gauge. Neither stem has a cap to unscrew but instead have a special plastic sealed end which automatically unseals when you press the fill device on.
On my other dual wheel trucks in the past and current Hino box truck...damned if I can remember ! I'm thinking the Hino is the same deal but maybe it does have screw on caps on the stems...which is a PITA in that situation.
Maybe he just needs a flashlight !
10-19-2008, 12:40 PM #3
The duals should be "clocked" on the 8? studs (Ford = 7?) so that the slots in the wheels allow access to the inner valve stem. I was told that the valve stems should be clocked 180 degrees apart between the duals (for balance? never heard that from anybody else)
To be sure you need one of those "double-sided" chucks.
I have a setup kinda like this, except older.
Also, when filling Load Range E tires they often run at 80psi, so the "free air" stations won't even get close to that...60psi if you're really lucky and most of the time patience runs out about 45.
If your duals are clocked such that the inner valve stem is hidden behind the structure of the outer wheel, you'll never get it filled...don't ask how I know
10-19-2008, 12:41 PM #4
And maybe the wholes on his outer rims were not positioned in the proper location...is that possible? Seems like there is a dog on a spacer or the inside wheel which prevents that.
Maybe he does just need a flashlight.
ahh...matt beat me to it.
Last edited by bluechipper; 10-19-2008 at 01:11 PM. Reason: splng...and matt beat me to it...gotta work on my typing;)
10-19-2008, 01:09 PM #5
It might be that until you put the "extension" on the inner valve, you need to remove the outside wheels to access the inner tire. Very stupid design but the extender is not "stock" on some truck chassis. A good tire shop should have the right extension, unless there has been a lawsuit somewhere. Good luck, Dave
10-19-2008, 01:17 PM #6
You'll find that there are the "usual" type of air chuck and gauge on the market. The filler end of the usual types are at an angle. The best type for dual wheels has the air filling hookup sticking out straight. This type is not usually found at Auto Zone or other chain store, but more likely to be found at heavy truck suppliers, and usually at NAPA stores too. You'll be much happier with that type of tool for your dually.
10-19-2008, 01:47 PM #7
Proper stem on the tube is the key, if tubeless, then angled long reach stems are available. The bent, or angled, long stem makes it easy to check the pressure with a double sided air chuck.
My F450 has hosed out extensions, so both tires are aired from the front, stems on tires are 180 degrees to each other. I will take a photo if I can remember.
Very important to check the inner tire air pressure, it is out of sight and out of mind. We do a lot of travelling on a livestock show circuit in the summers, pulling a 35 foot trailer. Lots of folks at the shows have dually trucks, its amazing how many low or flat inners I notice when at the shows, I run around the parking area with a hammer and tap the tires. When I tell the driver, the first answer is Huh? How do you check air pressure??
10-20-2008, 06:04 AM #8
truck-n-tow (there's others, can't remember their names right now) tow truck supplier sells a braided stainless hose valve extender for about 60 bucks for the set, comes with 4 hoses, on for each tire, and a little tab that mounts to the hub bolts. I have 'em on my dually, makes filling wherever with whatever a breeze.
can't believe some of you guys who've had duallys a lot longer than I've had mine don't have these things
Matt....8-lug on a Ford same as everyone else
10-20-2008, 08:11 AM #9
As Mat said you need to line up the D holes in the rims (by rotating the rim on the studs). Sometimes you can get missmatched rims, one with 4 D's and one with 5 D's.
You also need the double end air chuck and there are different styles of those. I have even had to bend the tubing on a chuck to fit some duallies. NAPA or a Semi truck stop should have them. Make sure it will fit your rims.
RV stores carry stem extension hoses if you want to go that route.
I drove and worked on semi's for 30 years, I learned to POP the inside tires with my toe to check for pressure or flat. It's not a direct kick, more of a twist and kick. Listening for a different sound than aired up tire. Kick the outside tire and compare sound.
10-20-2008, 08:19 AM #10
77, there are even handier units than your extensions called "Cats Eye". They have a hose for each tire (the tires are connected together), a central fill port, and a built in pressure gage that looks like a cats eye. If you can see the pupil in the cats eye, the tire pair is low. There is also a valve that will close the port between the two tires in case of catrostrophic leakage.
The units must be purchased for a specific tire pressure. The web site lists them down to 60 psi. They are also available for single tires. I have a set on one trailer with holes in the aluminum rims that are to small to reach my hand through to remove the stem cap.
10-20-2008, 09:32 AM #11
10-20-2008, 11:01 AM #12
10-20-2008, 11:02 AM #13
10-20-2008, 12:37 PM #14
10-20-2008, 12:45 PM #15
Edit - A little googleing makes it appear that they may still do the 7 lugs wheels on a "light duty" f250 based on the F150 but I can't be sure.
10-20-2008, 10:39 PM #16
Any 7 lug Ford I've ever seen was a stock hubcap...
A very convincing one though.