Community Forums

zippinbye · 02-01-2021, 11:38 AM

As would be evident by my other posts since buying our first DP coach, I'm new to game and have some things to learn.

My drive axle valve stem set up seems down-right weird to me. The inner wheel's stem is reachable through the outer wheel's two inch round hole. No problem, except it might not be suitable for mounting a TPMS transmitter, which is in the plans. Problem is, some "genius" decided to run a 3" angled extended stem inward from the outside wheel. It is partially inserted through one of the wheel holes. In order to check or air-up the outer wheels, one must pass through the 2" hole and attempt to get on the stem with a reverse-angle fitting. Very difficult to push (pull actually) the chuck onto the schrader valve. My air chucks have a trangular flange with a small hole on them, presumable for hanging storage or whatever. Not only does this flange make passing through the hole next to the stem difficult, it restricts the angles of approach to the schrader valve. The net result is me airing down the tire, whether I'm just trying to check pressure or add air. The only success I have had is a very difficult and awkward reach between the tires with either a independent digital pressure gauge that holds its displayed reading long enough for me to get the gauge back in sight, or with a straight air chuck to add pressure.

My first air check/service took nearly two hours for the back, while the steer axle took maybe five minutes. This is stupid and unacceptable! If the extended stem on the outer were about 1/2" shorter, it could be rotated 180 degrees to face outward, but it impacts the wheel hole preventing re-orientation. To me, it seems like this outer wheel would have been good with a "shorty" stem , either straight or angled out. Whoever configured the wheels this way went to some effort to make it very odd and difficult to service the air. Am I missing something? I've done a Google search and looked around Youtube and haven't found a dually air configuration as unfriendly as mine. I actually expected to learn that this style of valve stem orientation is a trick with a purpose, adopted by truckers decades ago. But it does not seem to be so.

Even if this set-up could be explained as sensible somehow, it doesn't work for me and I need to improve the situation. A pending tire purchase provides a perfect opportunity to get it right; just want to know the best way to go and get all the parts on hand before buying the tires. Since it's been called to my attention that my coach info is not showing up in my signature, here's what I have: 2005 Newmar Dutch Star M4023. It's a non-TAG with real aluminum wheels.

I came across the Wheelmaster WM 8005 inflation kit that uses a flexible braided hose extension and the schrader mounted to the wheel center cap to route air back to the inner wheel. The wheel cap bracket is a rivet-on affair that is tall enough to thread on a TPMS transmitter. Looks like a good solution, as would be a short outward-facing stem for the outer wheel.

Thoughts and recommendations for a better way?

Argosy · 02-01-2021, 11:49 AM

You need a dual head chuck to fill and check the tires, you'll be down to 5 minutes with the rears also.

https://www.amazon.com/s?k=milton+ai..._ss_ts-a-p_5_7

If you get the 'lock on' type you can hang it on the valve stem and it will stay without holding it in place.

Skip Y · 02-01-2021, 02:32 PM

Zippinbye, agree with you completely - what a pain. Some thoughts: the inner dually on many coaches is steel while the outer is alum, meaning you won't typically rotate the inner to the outer. That being said you could have the tire installer mount the new stem on the outer to point out instead of in.
Another option is to install a high quality stem extension. I have used Crossfires on my last 2 coaches. It's a single point supply with an internal 'check valve' that won't allow both tires to go flat if one's leaking. It also has an indicator showing normal or low pressure so you can visually see if there's a problem

alank · 02-01-2021, 04:41 PM

To answer your question "Am I missing something" Yes, you're missing something.
If you compare all the aluminum wheels, front & rear, you'll notice they are all exactly the same, and will work for front or rear installation. Something that is very important when you are preparing 100,000 tires & wheels for installation so you don't have to hunt & pick a wheel to find one for the front as opposed to one for the rear.

Just put the inside dual on a 1 1/2' block, let the air out of the outside dual, take the nut off the stem carefully, slide it down into the mounting hole slightly to clear the wheel hole, and rotate. Then pull back out, tighten the nut so the stem is in your desired position, and air up.

dfuelman · 02-01-2021, 05:32 PM

My first coach (Coachman Mirada) on a Ford F-53 Chassis had this same issue. I would literally have to jack up the RV and remove the outer wheel and tire to air up the inner tire. It SUCKED!

I finally went online and purchased a set of valve stem extenders. They are flexible stainless steal air hoses that screw onto the valve stem of the inner and outer tire and mount under the chrome lug nut simulators, allowing you to check and add air to both inner and outer rear tires with ease. Any decent RV dealer or tire dealer should be able to help you out if you are not sure what kit to buy. They are specific to wheel combo. but not terribly expensive.

David 70 · 02-02-2021, 06:37 PM

You say you want the parts on hand before you start. Are you purchasing the parts and taking them to the tire dealer? Any good dealer should have the parts to get the right fit.

TampaDave · 02-03-2021, 09:42 AM

For the inner you need a valve extender. I like the kind that has a gasket that stabilizes the thing in the wheel hole, although I currently have the flexible kind until I get around to it.

For the outer, you can't set it up sideways like a car tire cuz the hub gets in the way. Angling the valve extender to the outside makes it vulnerable to curb strikes. I think that's why it's angled in.

You get used to it. Gator caps help (google it up)

TPMS is cool but I dunno. Technically you only have to check once a week, plus if you go from hot to cold, or from high altitude to low. But it's easy to make it part of your daily routine.

I always hit the Flying J first thing in the morning, that's when it's the most quiet. Pick a lane that has at least one air hose, if you like. Takes a minute to gas up, plenty of time to check oil, tires, coolant. Clean the windshield. When your tank's full, pull up to the line, go inside and get your Monster and your breakfast pizza (the best part of waking up!)

Note that's not really your cold pressure. If the Flying J is right around the corner, it's probably close enough. If you have to drive down to the next exit, better to get a baseline during your morning walk-around, while the rig is airing up.

Parenthetically. Flying J is pretty awesome; among other things they will take your Good Sam card. Kinda cool rapping with the truckers. EZ in and out is pure bliss.

You can weigh your rig -- which will give you an idea of what tire pressures you're supposed to be running -- just pull up on the scales like you own the place and talk to the nice lady through the box.

Air-wise, though, it's aggravating, how many truck stops don't have it. Mainly because for some reason people love to swipe the air chucks. Barbarians.

Eventually I'm either gonna figure out how to air up the tires from the onboard pump -- which is trickier than it sounds -- or just buy an electric air pump. Which in my humble opinion would be a more worthwhile investment than TPMS, if you're only gonna buy one.

Depends on your tires. My last set, you had to get the pressure *just right* otherwise it handled like dogmeat. (Specifically, too high a pressure for your weight is rough, and makes it want to fishtail in the wind.)

So, my old tires were rated for 120psi, based on my weight, with a bit of a safety factor, 95psi was about right. Any more was bad, any less was real bad, TPMS might not have been a bad idea eh.

My current set, I can just pump em up to max and they are fine. They are rated for 5600lbs @ 110psi, I'm running 4930, and that's probably close enough, and why they ride fine for me at max pressure. My rear tires are now kinda set-and-forget, the daily check is just for safety.

You asked me what time it was, and I told ya how to build a clock. All in the spirit of thinking about what I'd wished people told me, when I first got this rig.

Ray Lenning · 02-03-2021, 12:03 PM

Dually Valve kits arena piece with the rubber stabilizer to support the inner valve stem . No need for extensions and one less place to leak . Screw on TPMS sensors can be used .We had extensions before and had a leak on an inside tire were the extension screwed onto the valve stem . Heres a link to your tire supply , the can help get the correct kit for you coach

https://yourtireshopsupply.com/categ...lly-valve-kits

Poohbear7278 · 02-03-2021, 03:09 PM

Poohbear7278 · 02-03-2021, 03:10 PM

Use these on the outside tires

RKins · 02-03-2021, 04:41 PM

Quote:

Originally Posted by TampaDave

For the inner you need a valve extender. I like the kind that has a gasket that stabilizes the thing in the wheel hole, although I currently have the flexible kind until I get around to it.

For the outer, you can't set it up sideways like a car tire cuz the hub gets in the way. Angling the valve extender to the outside makes it vulnerable to curb strikes. I think that's why it's angled in.

Not true. I went to a tire place that had the knowledge to work on big tires and asked if they could turn the outside stem so it points out enough to be inside the rim still - "No Problem", they didn't have to remove the wheel, aired it down, broke the seal, reached in and turned it where I needed it. One they couldn't budge, so they replaced it.
Now I can air up the outer tires easily with a flow-thru TPMS sensor attached and the hub is not a problem.

fasha · 03-21-2021, 07:50 PM

I'm always finding great fixes here. I've been taking my hubcaps off to get at the inner tire stems because I can get my hand in the rim holes. They're easy to take off, only 2 bolts, but still a bit of a hassle

Jim_HiTek · 03-21-2021, 08:23 PM

Valve extensions have been around for decades for this job. In the US, they charge $120 per set which is rediculous as they are imported from China and once you find them, a set is under $20. I was lucky last summer and found a set for around $25 or so. Anyway, here's what they look like: Dually valve sets for RVs