Tire Presure Monitoring Install

[Tom and Pam Brown]

Bought the safegaurd TPMS.  Installed on all six wheels.  The only issue is the outside tires in the rear have metal valve stems that turn to the inside of the wheel.  Once the sensor is installed, there is no way to add air without removing the sensor.  Anybody else have this issue and how did you resolve the need to removing the sensor to add air?

[Edward Buker]

Tom,

There are rigid stem kits that face out and use a rubber grommet in the outer wheel hole to hold the inner stem as it passes through. The outer wheel stem is U shaped and faces out. The only issue is you would have to have the rear tires removed and remounted to have these installed. They are better then most any other system from a leak integrity and ease of fill and pressure check point of view in my opinion. I had braided hoses before. I bought mine from Les Schwab in Coberg OR and they shipped them to my home in AL. They will want to know the coach type, wheel type, specifically the shape of the hole on the outer wheel. The price was $120 plus shipping.

Later Ed

[Steve Huber Co-Admin]

Tom,
Loosen the nut at the base of the rigid stem and  turn the stem to the  outside. It might be a tight fit getting it past the wheel on the inner side of the opening but it will make it if the nut is loosened enough. Then tighten the nut. You shouldn't lose any air.
Steve

[Mike Groves]

Tom,

First I tried Steve's suggestion, but I had a "professional tire service" do it.  One week later I returned to my coach in storage and the tire was flat.  Upon calling Les Schwab, the professional tire service who did it for me, I was told I'd have to pay for the service call.  A kid came out, "pumped up" the tire, but said he couldn't fix the issue so to come by Les Schwab.  I stopped in, and I was blamed for wanting to have that done (Steve's suggestion) - it was my fault for asking - and I should have known there would be consequences - a possible leak.  Well, I disagreed pretty strongly and wound up not having to pay anything.

So, then I went ahead and even though the tires looked great with only 20,000 miles on them (but 10 years old), I had 6 new double coin 606+ tires put on, along with, as Ed suggested, a set of new stems, one of which pokes out through a rubber grommet from the inner rear tires through the outer rear tires.  I think my outers are both straight, though, just like on the front tires. 

I then purchased the TST TPMS product with the flow through sensors so that I could air up without removing them.

The rear tire stems cost $120.00 I think it was, which certainly seemed steep to me and yes, you do have to have the tires off, but I was buying all new tires anyway.  I forget what they were called but next time I go to the coach (Tuesday) I can find the receipt which should name the product if you're interested.

I've had only a minor issue with the rear stems in that I thought one (on the outer rear) leaked, but I filled it back up and haven't had a problem since.

Mike

[Tom and Pam Brown]

I do not have the u shaped stem, the stems are straight to the inside. The sensor fills up the hole so much you cannot access.

Thanks for the input.

[Gerald Farris]

Tom,
I have rotated the valve stem on the outer rear tires on 4 different coaches, and I have never had a leak in one after rotating the stem. I always rotate the valve stem 90 degrees for easy access to inflate the tire and install TPMS sensors.

Gerald

[Fred Brooks]

     Hi Tom & Pam,

            Glad to hear you resolved your tire issues. I commend you on your choice to replace 10 year old tires and put the "correct extenders" with the optional TPMS system. Money wisely spent.

       This subject usually finds itself under the heading of "out of sight, out of mind" (kind of like batteries). The reason I am responding to this post is for all the "Newbies" and those who don't check there tires every time they stop while in transit. Over the years, I have made 10s of thousands of dollars repairing all the damage that dual tire falure has caused. There is lots of energy from a tire that comes apart and destroys holding tanks, wheel wells, storage compartments, electrical and in some cases propane plumbing.

       The reason we see all those "Road Alligators" lying on the freeway is usually a tire failure because of low tire pressure which results in overheating and then disintegration. The worst offender is neglect followed by flexable extenders that are flopping around or chaffing against an edge. If you have this type of extender, please inspect it and secure any loose braided hoses with grommits or other method to stabilize it. Every pot hole makes it move and with enough heat cycles it will "FAIL".

     I strongly recommend the method that has the valve stems facing outwards with the inners secured with a grommit where it goes thru the outer wheel rim hole. It makes the TPMS sender easy to install and add air if needed. If your installing new tires spend the money and put on new metal valve stems. Rotating old or original stems which disturbs the inner rubber seal is kind of gamble "sometimes you get chicken and sometimes you get feathers.     Regards, Fred

[Edward Buker]

Fred,

Very good post for the new owners of coaches. A little more understanding of the tire inflation importance might help. These truck tires are not held together by the rubber components, they are held together by closely spaced steel cables in the sidewall spaced less than 1/4 inch apart. When the internal pressure is to be kept above 60lbs or so, to carry the load, the tire construction changes from a rubber sidewall to one with steel cables. What makes the air pressure so critical is that the flex angle of the sidewall increases with low inflation and therefor the flex angle of the steel cable increases. Each rotation the cable goes through a cycle as it meets the road. Heat does not cause the failure of the steel cable, flex angle and the number of cycles does and you can picture that by bending a steel wire back and forth.

You can fatigue the cables very quickly to point of failure with low inflation over just a few miles. As Fred points out it is very important to never run one of these tires underinflated which is very different from a car in that a car tire will survive longer and may be fine when it is then returned to being properly inflated. The steel cable sidewall on the other hand may be irreparably damaged.

I am also an advocate of demoisturized air in our tires if your coach spends time sitting for extended periods. There is a more obscure failure mode related to that issue.

Later Ed

[Mike Groves]

Fred,

I think you were probably referencing my post in regards to new tires, along with the straight valves on the rears.

At any rate, given an initial pressure (per load and tire manufacturer's numbers), what is a good low alarm limit to set into the TPMS?  A good high pressure alarm value?

Thanks,
Mike

[Fred Brooks]

     Thanks Gerald, Ed and Mike for your replies,

      I am not a tire engineer nor any kind of authority concerning tires. I'm the guy who gets to listen to customers and insurance companies after the fact. After 44 years of listening and now the proud owner of a 2000 Marquis, I surely want to protect what I have worked so dearly for.
 
     My coach had the original tires dated july of 1999 with 53236 mies on them. Incidently the info label behind the drivers seat on the wall said 11R-22.5 but mine had 12R-22.5 on them ( another inigma to investigate). Anyway I replaced them after purchasing the coach.

      I'm kinda the CSI person the insurance guy talks to and advises him on cause and effect. Almost always the tires are over 8 years old and the extenders are poorly installed and neglected. Now I know this is a subjective observation but surely consistant. Now that I'm driving an 18 ton coach, I am aware there is only an inch and half of rubber between me and meeting my creator.

    The sooner you know you have a problem, the more time you have to respond to it. To answer you Mike conserning low pressure alarms on your TPMS, my suggestion would be 10lbs below the recommended inflation on wall data sheet or the chart that states recommended inflation pressure based from the weight scale that the coach is supporting on that axle. This should allow for early morning departures below 65 degrees.
      Happy Trails and keep the shiney side up and the rubber side down, Fred

[Fred Brooks]

http://www.rvtirepressure.com/assets/images/extrapages/Michelin_Rv_Load_Inflation.pdf
    This is the chart I refered to for a guideline to approximate pressures after weighing you coach. Fred

[Adam Hicklin]

Can someone post a picture of the optimum valve set up please?

[Edward Buker]

Fred,

The wall plaques on these motorhomes were for the tires originally installed and may have poor information for what tire is on the coach right now. Your posts regarding the weights vs the tire manufacturers recommendation is by far a better source of info being specific for he current tire and size on the coach. I am sure you have seen your fair share of tire damage and have some war stories to tell. It is amazing what that supersonic shock wave can do.

Over the years I have dealt with two inner dual tire failures from properly inflated Michelin tires on my 89 Beaver Contessa. I spent quite a bit of time on the road putting things back together. It is always a mess after a zipper fail. That coach ran tire sizes that had weight ratings right at the max tire weight capacity. I had Michelin XRV tires and in that size and weight capacity they did not hold up. The Marquis I have now has some margin and I do not have to run at the max pressure and max capacity, much happier with that. I think if you are have to run max tire pressures for the weight of your coach on some axle, those tire situations should have even more due diligence to keep the pressures just right.

Mike,

Probably the best alarm limits will come from varying the limit window to be just outside of the range your tires run pressure wise based on your operating experience.  A window that is a little beyond what generates a lot of false alarms for sure, otherwise you will learn to ignore it.

Later Ed

[Mike Groves]

Ed,

I think the TST TPMS is configured at 20% above and below, which is way outside my comfort zone.  Bottom line since I am running mine at 105 (that's what I shoot for anyway) at 65 degrees, I do try to keep them all right there.  According to both Michelin and Double Coin, 105 all around gives me 35710 total, which I'm comfortable with, and which, in my experience gives me the best steering.  I know, I know, I should weigh my coach, but I haven't felt comfortable yet pulling into a scales.  There is a scales in Hubbard, Oregon (where mine is stored) so I could use those probably.  I guess you just pull forward and keep watching the display, right?

During my trip across country last year I never let it get below 100psi - adjusted it one time back to 105 in the Walmart parking lot one morning using the gizmo I built based on reading the forum and watching the youtube video.

Love the TPMS though!  Don't leave home without it!

Mike

[Edward Buker]

Mike,

 The scales I used had you pull on and they printed all the results for I think $15. I could do each axle, each position, and total for the coach. This scale set up did not slope off quickly along the sides so you could do individual positions but not all are configured so you can.

I run 115 for my fronts and 110 for my rears which is 5lbs above what my weights vs tire pressure call for. I think you might be running your pressures too low in the front and would consider going to 115lbs until you do weigh the coach. I am not sure of this but others with your year/model may want to chime in here.

Adam,

These are the rear rim stem shots for the extensions that I got from Les Schwab. Coach is pretty dirty after traveling TX, NM, and Colorado. Hopefully we will find a spot to wash it in our travels. I also use small extenders that seal that do not require removal of caps to take pressure measurements.

Last but not least, when I had my new tires and stems mounted at a friends shop, I fell in love with this tool given I had the job of filling the tires with air. It is sold by Snap On, made by Blue Point, with a lifetime warranty. The cost was $130. As I was falling in love with the tool, the Snap On truck pulled up to the shop, so I considered that a sign and bought one. I have had several cheaper versions that simply are hard to read and do not work. This unit grips the stem, locks on and stays put and does not leak. It has a large readable display where I do not need my glasses on, the squeeze handle fill allows plenty of air flow, it also has an illumination feature if you need to read it at night, accurate to 1.5lbs if I remember right. It can be used just to check pressure or fill as needed. I measure pressures daily before driving and this tool has made that task easy. More than I wanted to spend but glad I did...last one I will ever buy.

Later Ed