Tire Safety System

[gmcbuffalo]

Here is an interesting tire monitor that replaces your value stem.


http://www.beru.com/download/produkte/fachaufsatz_tss_lkw_e.pdf


GregM

[Joe Cannarozzi]

It does say for standard instalation not for retrofitting but a great product and example of the bennifits.

What are you waiting for?

[Jon Wehrenberg]

Maybe I am not as quick to embrace technology as some, but while I see the merits of any system to alert a driver of a loss of tire pressure I also see some drawbacks.

It is at best a pain in the a$$ checking tire pressures. Those who routinely check their tire pressures will agree there is nothing more frustrating than doing it, and then having the Schrader valve on the inner drive tire decide it does not want to seat. But despite the effort, I also feel around the tires to see if I can sense the start of uneven wear or feel something in the tire that should not be there, like a nail.

If I had a system like that I would probably not check my tires or at least not check them as often. And then what would be the possibility the sensors would fail to alert you of a low pressure problem?

[win42]

If I had a system like that I would probably not check my tires or at least not check them as often. And then what would be the possibility the sensors would fail to alert you of a low pressure problem?[/QUOTE]

John outside of the thrill of feeling a tire up have you ever really felt any protrusions or bumpy surfaces? Sorry the devil made me post it.

[Jon Wehrenberg]

Harry,

I wish I could say no, that I never have problems, but over the years I have felt the little waviness in the outside edge of the tire that says it needs an alignment. I have felt nails and screws in the tires, and The reason I just replaced the tags is I felt a slight bulge in the sidewall going from just above the tread to the bead. It was not present on any other tire so rather than screw up the trip to FL I replaced the tires. I am sure it was related to a nail penetration a year ago just above the tread.

We have had two tire issues on the road in our years of ownership. I have not been able to get Michelins in our size (both were the 12R22.5) and the result is you put the odd size tire on the tags no matter which tire was originally damaged. Anything I can do to avoid the inconvenience of tire problems on the road is worth the effort.

[gmcbuffalo]

I'm going to Germany next month so I try and track some info down on this. In my trips to Germany they sure have some great looking buses.
GregM

[Jon Wehrenberg]

I wish I could say my experience with things that have a three pointed star have been positive.

[merle&louise]

[QUOTE=Jon Wehrenberg;11024]Harry,

I wish I could say no, that I never have problems, but over the years I have felt the little waviness in the outside edge of the tire that says it needs an alignment.

Jon,

I also check the front tires for waviness when checking the air pressure every morning. I have saved my 2 steering tires by catching an alignment problem early.

Maybe I'm just a bit anal, but I like checking the tires and adding air to keep them up to the exact pressure required by Michelin.

Checking air pressure is just as important as checking oil and fluid levels; it should be done every morning when on the road.:D

I just look at it as part of the fun;)

[garyde]

Tuga, I wish I had your proactive attitude. I am sometimes remiss in checking everything. Gary

[rfoster]

Me too Cosmo!:cool:

[garyde]

Me too Cosmo!:cool:

The cats out of the bag!

[Jon Wehrenberg]

Gary,

You should include your tires in your pretrip inspection and give them a really good look. We learned this the first trip. The tags were scalloped a little around the edges, but there was plenty of tread. I never gave it a second thought.

It turns out the tags will eat themselves up in very few miles if things are not right. They did. If you have a tire problem, with your tire sizes my guess is you will be parked for quite a while. All it takes is one experience thousands of miles from home to make you a believer.

[Orren Zook]

Gary,

You should include your tires in your pretrip inspection and give them a really good look. We learned this the first trip. The tags were scalloped a little around the edges, but there was plenty of tread. I never gave it a second thought.

It turns out the tags will eat themselves up in very few miles if things are not right. They did. If you have a tire problem, with your tire sizes my guess is you will be parked for quite a while. All it takes is one experience thousands of miles from home to make you a believer.

Jon,

Were you able to determine the cause of the accelerated wear? Bushings, inflation, alignment??? I have had my alignment shop say that front tire wear can also be caused by worn bushings on the drive axle. I had seen this on trucks, mostly with the Hendrickson suspension where you can watch the axles track in and out when throttle is applied or lifted - but had not given much thought to the conditon of the the suspension bushings on the drive axle of my bus because of the low mileage.

[Jon Wehrenberg]

Scalloped edges was a common problem on 12R 22.5 Michelins in the early 90s. When I got the coach there was slight scalloping that was blamed on balance or alignment (according to the genius tire guy).

I had the front tires with the scallops placed on the tag because of advice from the tire dealer, had the tags moved to the front and the fronts balanced with weights and the front aligned. The coach was almost new so wear was not an issue.

As it turns out the advice about moving the tires to the tag was lousy. I now know if you want to straighten out a tire problem the tire needs to be on the drive axle. But thinking we were OK we left for our first long trip and after about 4000 miles I found the tag axle had enlarged the scallops right down to the steel belts on one of the tires. I later learned that tag axles are notoriously hard on tires, especially if they already have a problem and are out of balance. The last time I listened to advice on tires was from the guy that changed my tires. BTW, on the next set I had the coach re-aligned, and I used Equal to balance them, and I rotated them every 30,000 and they had 1/4 of tread on them when I replaced them at 130,000 miles.

[gmcbuffalo]

I was told my a manager at Les Schwab that tire scalloping is common on any floating axle. ie steers and tags.
GregM

[garyde]

Yes, thanks Jon. The curious thing about the tag is the wear. When I was in my 20's, I owned VW Buses. Those tires on the back transaxle wore on the outside edge too. I don't really understand why on a strait axle I would see edge wear. My Country Coach tag was the same.

[Jon Wehrenberg]

As Greg points out the "floating" tires are very susceptible to irregular wear patterns. Some tires are made specifically for these axles and some are made specifically for drive axles. I do not know the dynamics that creates that situation.

On the coaches that used 365 tires on the steers and tags, and 315 on the drive tire care is more critical than ever. When I had a tire wear issue I could simply place the tire in question on the drive axle and that unusual wear pattern was corrected over a period of time. Because of the steel inner wheels on 45 foot coaches or because of a wheel polishing issue doing that involves breaking down the tires and wheels, but at least you could salvage a very expensive tire when its wear was caught promptly. That option is not available on coaches with dissimilar tires so checking pressures and feeling for any wear problems becomes critical.

With the price of 315 tires now north of $600, I think a tire monitoring system that works should almost be standard equipment on the shells. I also think it should be the band type so there is no added potential for leaks, and I also think the battery life in the sensor should be five years to parallel the life of the tire. As long as I am bloviating I also think the sensors should display actual tire pressure and not just a low pressure warning.

[truk4u]

That's the beauty of Smart Tire, temperature and pressure at the push of a button.;)

[JIM KELLER]

Jon, This tire talk has made me curious about my tag axel function. I always lift it in tight turns but notice it never clears the ground. The bus squats down on the suspension and I deposit less rubber on the cement but the tire still drags. I suppose lifting the tag reduces the side pressure on the wheels so that by itself is a benefit. Is there a height adjustment that will make the tag axel tires clear the ground ? Seems like 40 footers clear the ground with no problem and 45's just squat down.

99 Country Coach 45XL

[Joe Cannarozzi]

The drive axle is slow to respond to the additional weight when you lift the other. The drive bags will first squat but will come back up and If given enough time the tag will completly clear the ground on our bus.

I think that completly up is for sure the best senerio, merily dumping the weight and not lifting is still prefferable and makes a huge difference.

Nobody is gonna wait every time they make a turn and I don't think that is what the designers had in mind.

Train yourselves to use this option frequently, it will save you money.
Most turns at intersections on secondary roads I dump it.
Whenever we pull into a campground I have got into the habbit of dumping the tag as the first step in dropping the toad. By the time I get done its off the ground. I also dump it on the way INTO the fuel island and truckstops.
We also leave the house and take it a couple of blocks to the main road on 2 axles. There are 4 bags on the drive axles thats double whats nessesary.

[Jon Wehrenberg]

Jim,

First a qualifier. I do not know if what I am describing below is standard on all shells, or if the converter has disabled the feature as I heard a certain large west coach converter did. Take the following with a grain of salt until you have verified it.

On 45 foot coaches that I have been beneath there is a device that is intended to prevent the rear of the coach from dropping when the tag air is dumped. Again, on the coaches I have seen from the underside, there is a switch that engages the tag axle air dump system when the steering wheel is turned to the extreme in either direction. When that occurs tag axle air is automatically dumped, and to prevent the rear from dropping air over hydraulic shock absorbers on the drive axle are brought into play, and they literally support the coach so it will not drop.

If you get under your coach, on the bulkhead forward of the drive axle will be a reservoir with a sight glass mounted in the middle. With the coach at the ride height, the reservoir should have the sight glass half full of Dextron III fluid. That is the hydraulic fluid which is forced into the hydraulic cylinders (which look like shock absorbers) that are mounted on the rear of the drive axle.

If you coach is dropping when the tag air is dumped, it could be because you do not have this system, the system is not functioning, or the system is low on hydraulic fluid.

Do not manually lift the tag as this may over-ride the operation of the system described above. There is insufficient information in my Prevost manuals to be able to say with certainty that what I am telling you is completely accurate.

[JIM KELLER]

Thanks Men !

[merle&louise]

How much air (psi) do you guys carry in your tag and how much in your drive axle tires?

I am told to put 110psi in the drive axle and 80psi in the tag. Any ideas why?
My rear tires are 11R80 24.5 Michelins and my front tires are 315/80 22.5 Michelins.

Why not have all three rear tires carry the same load?:confused:

[Jon Wehrenberg]

Bad advice was given to you Tuga.

The air pressure in the tires is related to how much weight they carry and the pressure that is required for that weight is listed on the Michelin web site under the specifications for your tires.

Because each of my axles carries a different amount of weight I have different tire pressures for the tires on each of my axles. If I weighed the coach from side to side I might even have more than three pressures.

Your first step is to have your coach weighed and once you know what each axle weight is you will find the correct tire pressures.

[merle&louise]

Jon,

How much air do you carry in the rear tires and what is the actual weight of the drive axle? How much air do you carry in the tag and what is the weight of the tag axle? How do both compare to the GVWR for each axle?

Do you think that I should weigh the driver's side rear of the coach and then weigh the passenger side rear? Would they carry different pressures if they differ in weight?

[Jon Wehrenberg]

Tuga,

Without going to the garage to verify I believe I am around 14,000 on the steer, 20,000 on the drive and 12,000 on the tag. When I looked up the pressures my steer needs to be 100 PSI, the drive 80 PSI and the tag 85 PSI.

I have not weighed the side to side on each axle because the scales I have seen don't have sufficient width alongside the scale to run one side of the coach on the scales at a time, so I over inflate my tires by 5 PSI. The actual pressures I run are 105, 85 and 90. Those were of a fully loaded coach with full fuel and water, all our stuff in the bays and closets full of clothes.

If you were able to weight the side to side differences you could be more precise on inflation pressures. I have to assume that is splitting hairs however because on our coach with a full fresh water tank the weight is biased towards the passenger side and as that tank is emptied and the holding tank is filled the weight shifts toward the driver's side.

As far as capacities we are approaching the limit of the steer axle, but we are below the other axle limits. I can't give you specifics without getting the weight ticket and the limits from the data plate. We do not exceed any Prevost limits.

[Jon Wehrenberg]

I did a little research in the Prevost technical diagrams and found the Tag axle unloading system is as I described. According to the wiring diagram the switch which activates it is sensing the position of the Pitman arm in the steering box. If the speed is below a certain value the air is dumped from the tag and hydraulic lock valve is energized. It is all automatic.

I have seen the switch actuator relating to the Pitman arm on my coach and the steering wheel must be almost at the extremes of its travel in order to actuate the system. I do not see any provision for supporting the rear of the coach if the tag axle is lifted manually via the switch behind the driver's seat.

[merle&louise]

Thanks Jon, I looked up the psi that Michelin suggests for my application and the front axle(315/80 R 22.5) is right on the money @ 130psi. It is rated at 17,640 and the actual weight shown by the scale was 16,920 (full fuel and water). Michelin shows with 130psi per tire the supported weight would be 9090# on each tire for a total of 18,180#.

I'm going to weigh the drive and tag separately as soon as I can get to it. I think that I will be o.k. because Michelin shows an 11R24.5 L supporting dual tires @ 12010# @ 105psi and a single tire supporting 5550# @ 80psi. All adding up to 35,120# and my actual weight is 33,180.

I am still going to weigh the drive and tag separately to see if the pressures need to be adjusted up or down.

Thanks for the help, I really appreciate it.

[Larry W]

The prevost manual that came with my 99 chasis states on the 45'xl the tag will not lift off the ground but will unload. 40' will lift off the ground. The manual also states to unload the tag when making sharp turns or for additional traction on slick surfaces. This worked for me in a rest area in Utah we slow me stopped with the drive wheels on ice.

Larry W
00 Royale Coach

[Orren Zook]

On the subject of wheel/tire balancing here's a link to a promising web page: www.dynabeads.com

[gmcbuffalo]

Has anyone used this device or heard of it?


Trikor.com

http://trikor.com/Merchant2/TSG/TPM-P%20RV%20Installation.pdf

Seem like a good solution for tire monitoring upgrade to any coach. Because a bus have so much metal they recommend an antanae be installed that runs down the belly of the coach to help pick up signals.

GregM

[Joe Cannarozzi]

Greg

We have somethig similar by Dorian but this product looks to have addresed a shortcoming on ours.

We have to remove the sensors to add air to the tires and on the product you have here it allows you to air up right through them. Very nice.
I love ours best 700 I've spent on anything. Here is what our sensors look like, there is a battery in them that has a 5 yr shelf life. Replacment cost 50 a tire.

1209

I think something like this should be standard stuff on all new conversions.

Oh Jon, I'm still fixin to nitrogen up the tires, soon as we get our buts down south again:p

[Ray Davis]

Am I missing something here? The sensor which attaches to the valve stem seems huge. At best, I would guess that would unbalance the wheel? AT worst it would seem to add to the possibility of valve stem failure?

Ray

[Joe Cannarozzi]

Ray we have never experienced any of those conditions but we do run the ballance rings on ours along with the sensors. The manufacture has addressed this issue with a note about there insignificant weight that at the moment I can not remember.

We do also have them on the PU we pull and it has conventional wheel weights and there is no wheel imballence on it either. If they dont throw the ballance off on those smaller tires it certianly isint going to affect a 12-22.5.

[Ray Davis]

Joe,

Thanks for the response. But, if I look at the little bitty cap in your picture, versus the large thing that attached to the valve stem in the Trikor product, there's a huge difference in size.

Are we talking the same kind of thing here?

Ray

[Joe Cannarozzi]

Ray

Yes I think so. The other device allows you to air up the tire right through it where ours has to be removed. It is a convienience issue and if I were in the market again would be something I would like. That device also gives temp. and although I don't know how usefull that would be, concidering that increased pressures are directly connected to the temp, that might be kinda nice too.

[Ray Davis]

I'm not doubting that this could be a beneficial gadget, however I'm concerned with size/weight. Your gadget looks to be smaller than a quarter dollar, while the Trikor thing looked to be roughly golf ball sized.

How does that affect valve stems, when we've heard other reports (by Jon), where stem extenders cause failure?

ray

[Jon Wehrenberg]

If I was to install some type of tire pressure monitoring system in my coach I would focus on one with an internal sensor.

However, none of the systems now available are without their limitations. The internal type may have range issues. The reports I have seen on one brand indicates the sensor signal sometimes has problems reaching the receiver on the dash. I also have questions if that type can be used if Equal is used to balance the wheels.

Battery replacement on the internal type requires the wheel / tire to be broken down. That makes battery life a serious consideration, because even if you want to break down your own tires you will spend some serious time and effort.

The external sensor that mounts on a valve stem brings with it another set of problems that Joe has addressed. Once the sensor is installed it literally opens the valve. Instead of having two valve stem seals the external sensor leaves you with a single seal. That was the problem with the LED type that I tried. When I installed them I soaped them to check for leaks and they were OK. By the time I got to OSH, two were leaking.

Joe still runs that risk, but his are obviously better quality than the ones I tested. Unless a second valve stem is installed like Joe did, every time a sensor is removed and reinstalled, such as to add air, the potential for a leak increases. While valve stem valve leaks are not a factor on wheels with these sensors, the probability air has to be added from time to time is a given, and unless someone uses the second valve stem I question the life span of the sensor seal, something critical because the sensor opens the valve so it can sense pressure and you are totally reliant on that single seal.

[gmcbuffalo]

I talked to the rep for Trikor about the issue of balance, he said it light and you do have to balance the tire with it on.

On the valve stem issue he recommended using the cable extended if your are concerned about it. Having had a wobble long stem issue on my inner dual this is a concern of mine. I don't know why you couldn't use the wire cable extenders attached close to the main stem and use loctite to keep them secure.

The device appears to me to have a valve core inside that you air thru and you can use a cap still for secondary seal.

I asked him if I could bring this product to the groups attention and he welcomed it and would look forward to your questions.

GregM

[gmcbuffalo]

I contacted Tim at Tikor about a POG discount and Tim offered the following to get this product.

[rfoster]

I read the proposal on the tire monitoring system with interest. How long is the warranty? What is the expected life of the monitors, receiver? What about the metal in the bus, does it interfere with the signal and if so what do you recommend? And lastly- Has anyone on the forum used them and can they recommed them?
Gregg: Please Pass these questions to the guy making the proposal
Thanks in advance, :cool:

[Joe Cannarozzi]

Looks like they are 7 yrs on the batteries, ours were 5, and the price is almost the same. Dash screen does not require batteries.

I think I paid 700 for it with 12 moniters, enough to put them on the toad too.

No external antenna was nessesary on ours.

[gmcbuffalo]

The proposal has an antenae in that attaches to the reciever that goes down the belly of the bus. On the sticks and staples type RV's don't need it but with all the metal in our it is recommended.

I'll pass your comments on.

GregM