Replaced rubber valve stems on Mercedes 3500HD-based Tiffin Wayfarer

[MarkMaxPayne]

Put over 2,150 miles on the Tiffin Wayfarer in 4 days this last trip. Glad I had my TireMinder TPMS system. Heard what I thought was the furnace kicking on in the back for about 20 seconds (loud blower sound) then my TPMS went nuts telling me I had gone from 80lbs down to 0lbs of pressure on my passenger outside dual. Without the TPMS I don't think I would have known until the inside dual overheated and gave way...

Turns out the valve stem gave up and split right at the rim. There is a brass insert and it sounds like the value stem usually gives way right where the brass starts/stops inside of the rubber stem itself. I've also ran into this issue before on a Dodge RAM towing a 5th wheel (twice) so I've been trying to resolve proactively on my Mercedes 3500HD based RV, but could never find a shop willing to do it.

These rubber valve stems from the factory are only rated around 60-65lbs and when you run them at 80lbs it isn't a matter of if they'll give way, but when. Took me forever to finally find a tire shop willing to replace the rubber valve stems for steel ones. They all acknowledged they had to be replaced, but on the Sprinter rims everybody hates to do it as the working area is so small it is very hard to properly tighten the value stem nut and to install extenders on to that; nobody wants to spend the extra shop time and effort to do it. Also, they are shorter than the rubber stems so some of the extension hoses and angled extensions have to be reworked/replaced to make up for the longer run required. Lastly, even those are a pain to then reinstall given the little clearance for their own tightening nuts at the valve stem due to the very narrow rim clearances where the stem mounts.

I know when Mercedes ships a chassis to a manufacturer, they are in compliance with the ratings. A bare chassis weighs nothing compared to the built-out rig. However, once an aftermarket manufacturer then adds enough weight to require the higher running tire pressures I'm flummoxed how they are not required to replace the valve stems that are rated for 80lbs that they themselves recommend right there at the factory.

Anyways, my issue is behind me, but thought I'd share.

Best,
-Mark

[Skip426]

There are two different types of rubber tire valves , one for cars , another for light trucks , I won't quote max pressures for these , but with the metal tire valves rated to 200 psi. those are the best to use.

Lets see if this link to Tire Rack still works .

http://www.tirerack.com/tires/tirete...jsp?techid=208

Well the link used to go straight to the valve info , not any more. I'll see if I can fix that.

EDIT : Well spelling correctly helps .

Yes , using a tire valve at it's max rating , isn't a good idea .
Safe travels.

[Grn_Mtn_Boy]

You might also consider the possibility that your tpms sensor contributed to the valve stem failure. Extra weight on the end of the stem, spinning around with centrifugal force. That's why they have the rubber insert stem keepers. Some tpms systems suggest using metal stems only, for this reason. In any case, you made the right move. What brand of valve stem worked?

[MarkMaxPayne]

Originally Posted by Grn_Mtn_Boy

You might also consider the possibility that your tpms sensor contributed to the valve stem failure. Extra weight on the end of the stem, spinning around with centrifugal force. That's why they have the rubber insert stem keepers. Some tpms systems suggest using metal stems only, for this reason. In any case, you made the right move. What brand of valve stem worked?

My front tires had valve stem holders/grommets in the wheel covers to help the stems not flex. It was the outside dual stem that blew out though, which was connected to a set of valve stem extenders that were held in place by hard plastic grommets and bolts in one of the wheel holes to prevent any movement or flex. Because the valve stems on outside duals face inward vs outward, a number of manufacturers mount these extenders (that have bends in them) such that you can easily check your tire pressure and add air as though the stem faced outward. It was securely mounted.

That said you are right about TPMS sensors being a cause of valve stem flex if simply put on without stem protection or not on steel stems.

Best,
-Mark

[f14av8r]

Originally Posted by MarkMaxPayne

Put over 2,150 miles on the Tiffin Wayfarer in 4 days this last trip. Glad I had my TireMinder TPMS system. Heard what I thought was the furnace kicking on in the back for about 20 seconds (loud blower sound) then my TPMS went nuts telling me I had gone from 80lbs down to 0lbs of pressure on my passenger outside dual. Without the TPMS I don't think I would have known until the inside dual overheated and gave way...

Turns out the valve stem gave up and split right at the rim. There is a brass insert and it sounds like the value stem usually gives way right where the brass starts/stops inside of the rubber stem itself. I've also ran into this issue before on a Dodge RAM towing a 5th wheel (twice) so I've been trying to resolve proactively on my Mercedes 3500HD based RV, but could never find a shop willing to do it.

These rubber valve stems from the factory are only rated around 60-65lbs and when you run them at 80lbs it isn't a matter of if they'll give way, but when. Took me forever to finally find a tire shop willing to replace the rubber valve stems for steel ones. They all acknowledged they had to be replaced, but on the Sprinter rims everybody hates to do it as the working area is so small it is very hard to properly tighten the value stem nut and to install extenders on to that; nobody wants to spend the extra shop time and effort to do it. Also, they are shorter than the rubber stems so some of the extension hoses and angled extensions have to be reworked/replaced to make up for the longer run required. Lastly, even those are a pain to then reinstall given the little clearance for their own tightening nuts at the valve stem due to the very narrow rim clearances where the stem mounts.

I know when Mercedes ships a chassis to a manufacturer, they are in compliance with the ratings. A bare chassis weighs nothing compared to the built-out rig. However, once an aftermarket manufacturer then adds enough weight to require the higher running tire pressures I'm flummoxed how they are not required to replace the valve stems that are rated for 80lbs that they themselves recommend right there at the factory.

Anyways, my issue is behind me, but thought I'd share.

Best,
-Mark

Aluminum wheels and metal valve stems are the best solution.

Why are you running 80 psi in your tires? Every inflation chart I've seen indicates pressures in the range of 55 to 65 psi for the maximum axle weights on my 2020RW Tiffin Wayfarer. I run 60 in the front and 65 in the back.

[MarkMaxPayne]

Originally Posted by f14av8r

Aluminum wheels and metal valve stems are the best solution.

Why are you running 80 psi in your tires? Every inflation chart I've seen indicates pressures in the range of 55 to 65 psi for the maximum axle weights on my 2020RW Tiffin Wayfarer. I run 60 in the front and 65 in the back.

The sticker inside my driver's side door from Tiffin says to run them at 80 psi. Yes, the Mercedes factory sticker states a much lower rating, but that was for a bare bones chassis before the RV manufacturer built out on top of it.

Best,
-Mark

[f14av8r]

Originally Posted by MarkMaxPayne

The sticker inside my driver's side door from Tiffin says to run them at 80 psi. Yes, the Mercedes factory sticker states a much lower rating, but that was for a bare bones chassis before the RV manufacturer built out on top of it.

Best,
-Mark

Hi Mark,
I think you are misreading the Mercedes label. If your sticker is like mine, the pressures shown are for a fully laden (max axle weight) condition. Notice the cylinder images indicating a load. The owner's manual explains the label. Thus, unless you are overloaded, these are the minimum pressure you should run. I add a few pounds for changes in altitude but you most surely no not need to run at 80 psi. That makes for a rough ride, decreases the surface area of the tire that is in contact with the road (decreased traction), may result in uneven tire wear, and is higher than the valve stem rating. 80 psi is the MAX inflation pressure for the tire, not the proper inflation pressure for the tire.

[MarkMaxPayne]

Originally Posted by f14av8r

Hi Mark,
I think you are misreading the Mercedes label. If your sticker is like mine, the pressures shown are for a fully laden (max axle weight) condition. Notice the cylinder images indicating a load. The owner's manual explains the label. Thus, unless you are overloaded, these are the minimum pressure you should run. I add a few pounds for changes in altitude but you most surely no not need to run at 80 psi. That makes for a rough ride, decreases the surface area of the tire that is in contact with the road (decreased traction), may result in uneven tire wear, and is higher than the valve stem rating. 80 psi is the MAX inflation pressure for the tire, not the proper inflation pressure for the tire.

Yes, I am ignoring the chassis sticker. The NTSB requires that all RV manufacturers add a supplimental label that supercedes that of the chasis manufacturer without obscuring the original. Mine is located inside the front driver's door below that provided by Mercedes. Tiffin's label for my 2018 is attached. It says 80 psi... I'll reach out to Tiffin and see if that is simply the max.

Best,
-Mark

[dennish2024]

Just to back up what Max said, I had a 2019 Wayfarer and the door sticker said 80 psi. I traded for a 2020 Wayfarer and was a bit surprised when the Tiffin door sticker listed a lower psi. I still run 80 psi.

[stomp]

2018 wayfarer 24 qw 12000 mi: pre trip check list, the tires set to 80 psi per tiffin door jam label. I experienced 4 rubber valve stem failures in 3 weeks on road trip to ca. 5/3/21 sudden loss of pressure right front in heavy fast Fl. turnpike traffic, was fortunate to get on shoulder without damage, injury or loss of life. on 5/23/2021 sudden loss of pressure left front in heavy fast El
Paso I 10 traffic, again able exit without accident. all flats due to rubber valve stem failure. on his trip i had 4 rubber valve stem failures and i replaced the other 2 before they could fail. made it home to fl. with 6 new valve stems and 61 psi.

Originally Posted by Skip426

There are two different types of rubber tire valves , one for cars , another for light trucks , I won't quote max pressures for these , but with the metal tire valves rated to 200 psi. those are the best to use.

Lets see if this link to Tire Rack still works .

http://www.tirerack.com/tires/tirete...jsp?techid=208

Well the link used to go straight to the valve info , not any more. I'll see if I can fix that.

EDIT : Well spelling correctly helps .

Yes , using a tire valve at it's max rating , isn't a good idea .
Safe travels.

[FarmerJake]

2019 Wayfarer 24TW. We experienced a rubber valve stem failure a couple of weeks ago on the drivers side outer dually. Fortunately, our TPMS alerted us and we got off the road safely. Last year we had the same failure on the passenger side outer dually. On our wheels, the valve stem on the outer wheels point inward and a flexible braided stainless hose is used to bring the valve outside the wheel and through the simulator. In my estimation, the braided hoses are constantly flapping around putting a strain on the rubber valve stems, causing them to fail. This setup is obviously a poor design that is causing so many people grief.

I purchased solid metal Borg valve stems for all 6 tires and have an appointment to have them installed next week. Hopefully that will end this nightmare for us.

Tiffin is aware of the problem and at the very least they should notify Wayfarer owners and warn them!

[MarkMaxPayne]

Originally Posted by FarmerJake

2019 Wayfarer 24TW. We experienced a rubber valve stem failure a couple of weeks ago on the drivers side outer dually. Fortunately, our TPMS alerted us and we got off the road safely. Last year we had the same failure on the passenger side outer dually. On our wheels, the valve stem on the outer wheels point inward and a flexible braided stainless hose is used to bring the valve outside the wheel and through the simulator. In my estimation, the braided hoses are constantly flapping around putting a strain on the rubber valve stems, causing them to fail. This setup is obviously a poor design that is causing so many people grief.

I purchased solid metal Borg valve stems for all 6 tires and have an appointment to have them installed next week. Hopefully that will end this nightmare for us.

Tiffin is aware of the problem and at the very least they should notify Wayfarer owners and warn them!

FarmerJake,

My advice after they install the Borg valve stems is to pop off the decorative wheel covers and then carefully inspect their work by pushing and prodding the valve stems, hoses, extensions, etc. Really make sure the new stems are indeed on tight and are not loose and leaking air around them when prodded. As you shared the braided hoses put a lot of centrifugal force on the stems and if your wheel tech was lazy (or mad that he drew the short straw to do that job as replacing the stems and tightening the nuts correctly is a pain in the @#$%! due to the narrow clearances on these Sprinter rims), they'll leak while traveling at speed. Of my 6 wheels, I had to go back and pull two of them back off the rig and tighten the valve stem nuts down myself; one wasn't even what I'd call finger tight...

Next is to look at all the valve stem extenders where they come out at the decorative wheel covers to check to see if any are being worn down by rubbing on the wheel inserts as they flex at speed. If so, add some rubber grommets.

Good luck!

I do recommend owners of any rig on a MB 3500HD chassis with steel rims look to replace the rubber valve stems (then check over the tire shop's work).

Best,
-Mark

[f14av8r]

Originally Posted by FarmerJake

2019 Wayfarer 24TW. We experienced a rubber valve stem failure a couple of weeks ago on the drivers side outer dually. Fortunately, our TPMS alerted us and we got off the road safely. Last year we had the same failure on the passenger side outer dually. On our wheels, the valve stem on the outer wheels point inward and a flexible braided stainless hose is used to bring the valve outside the wheel and through the simulator. In my estimation, the braided hoses are constantly flapping around putting a strain on the rubber valve stems, causing them to fail. This setup is obviously a poor design that is causing so many people grief.

I purchased solid metal Borg valve stems for all 6 tires and have an appointment to have them installed next week. Hopefully that will end this nightmare for us.

Tiffin is aware of the problem and at the very least they should notify Wayfarer owners and warn them!

Ditch those stock wheels. Put a couple of thousand into new aluminum wheels and metal valve stems. Problem solved.

[FarmerJake]

Mark - thanks for the advice. I have my local mechanic doing the work and I plan on being there during the installation and watch what he does. I’ll be sure the valve stem nuts are tight and the stems are centered in the openings of the wheels and simulators. I also made my own stem “protectors” out of an old washing machine hose. They fit snugly over the stems and keep the stems from rubbing on the wheel covers.