Tires, TPMS, blowouts, etc.

[CharlesinGA]

Needs context.

Tyre shine, a generic term, cannot be said to ruin tyres.
I think i know the sticky, nasty-ass chemical crap that you had on your tyres (were they actually nearly new? date code?) some places use that stuff all the time, especially to cover up problems, it's a chemical, it's bad news for tyres, you can still find it it you try hard enough, but it's bad for rubber, don't ever use it.

Nothing made for tyres in the last 30 years actually kills tyres, and again, it should be water based, it's job is only 2-fold, to made the rubber appear more appealing and to protect the tyre from the UV rays of the sun.

Tires were a little older than I recalled, dated 3712 (just checked my photos), and I bought at the end of Sept in 2015 so they were about 3 years old. I think the owners (or their estate) installed the tires. It actually was an estate sale handled by a new RV dealership, Travel Camp in Jacksonville, new location, new building. The stuff on the tires was not very old, I suspect the broker had put it on as the motor home was on the lot for 6 months or so when I bought it.

The only thing I would ever put on anything rubber is Aerospace 303 as that is well known and does not harm rubber in any way.

Charles

 

[DonTom]

rear tires set to 75-80PSI and fronts around 55-60PSI on a Tioga Class C.

I was looking for something unrelated in one of my manuals in this RV and I came across this note in my own writing with a date mentioned of 2, April 2009.

It says front tires are "Federal MS A/T 225/75R16 use 63 psi, 65 psi is max."

Says rear tires are "Firestone Transforce LT 225/75R16 115/112R use 73 psi rear, max is 80 psi".

That was in 2009. Perhaps after I got this thing weighted and checked the tire charts on line, not sure.

But now my front tires are "Transforce HT" and my rear tires are "Whankook Dynapro HT".

I wonder if these tires require a different PSI. I guess I will have to start from the beginning and get this thing weighed and then check the tire tables online for these brands.

Is if Flying J that usually has the weight stations that can check RVs? I know I have done it once, but it was a very long time ago and I am not sure if it was for this RV or the older (1979) one I had before this Y2k RV.

-Don- Borrego Springs, CA

 

[Larry N.]

Is if Flying J that usually has the weight stations that can check RVs?

There are lots of truck stops around with CAT signs, which indicate scales are on-site.

 

[BrunoMTP]

I was looking for something unrelated in one of my manuals in this RV and I came across this note in my own writing with a date mentioned of 2, April 2009.

It says front tires are "Federal MS A/T 225/75R16 use 63 psi, 65 psi is max."

Says rear tires are "Firestone Transforce LT 225/75R16 115/112R use 73 psi rear, max is 80 psi".

That was in 2009. Perhaps after I got this thing weighted and checked the tire charts on line, not sure.

But now my front tires are "Transforce HT" and my rear tires are "Whankook Dynapro HT".

I wonder if these tires require a different PSI. I guess I will have to start from the beginning and get this thing weighed and then check the tire tables online for these brands.

Is if Flying J that usually has the weight stations that can check RVs? I know I have done it once, but it was a very long time ago and I am not sure if it was for this RV or the older (1979) one I had before this Y2k RV.

-Don- Borrego Springs, CA

Hi Don,

That sounds about right. I wouldn't expect much difference between tire brands re: load capacity at different weights as long as they are all the same size and are all Load Range E.

This should help you find a place to weight your rig.

https://catscale.com/cat-scale-locator/

 

[DonTom]

This should help you find a place to weight your rig.

Thanks for that handy link. I passed up three such places without knowing just coming down here from north of Salton Sea.

When I leave here, I will be going right by:

Love's Travel Stop
Hwy 86 & Martin Rd Westmorland, CA

I will get it done there.

-Don- Borrego Springs, CA

 

[F2CMaDMaXX]

Slightly related question, can i weigh my TT with it still hooked to the tow vehicle, if just the TT's wheels are on the scale?

 

[CharlesinGA]

Slightly related question, can i weigh my TT with it still hooked to the tow vehicle, if just the TT's wheels are on the scale?

Fill your fuel tank, stop and disconnect the weight bars. Pull the rig onto the scales properly, they are in three segments, front axle, rear axle(s), trailer axle(s). When the person on the speaker says they have your weights, pull off the scales, drop the trailer, leave the hitch in the receiver, weigh just the tow vehicle, front axle, rear axle(s),

Weigh tickets will give you weights for the axles separately, except the trailer.

1) Take the combined weight of truck/trailer on the bottom of the ticket, and subtract from it, the weight of the truck when weighed alone, The result is the weight of the trailer.

2) Take the trailer weight you just calculated, and subtract the trailer axle weight from it. The result is the tongue weight of the trailer.

3) Take the tongue weight, and divide it by the total trailer weight from step #1. The result is the percentage of the tongue weight to the total trailer weight.

My truck and trailer as an example:

The truck by itself, a 2003 RAM 2500 std cab, tradesman model with 5.9L HO Cummins and 6 spd manual transmission and a LEER topper, and a full tank of fuel.
Front axle, 4060 lbs
Rear sxle, 2860 lbs
Gross weight, 6920

The truck and trailer on a ball, no weight distribution, loaded as described above.
Truck front axle, 3680 lbs (lost 380 lbs)
Truck rear axle, 4040 lbs (gained 1180 lbs)
Trailer axles, 5060 lbs
Gross combined weight, 12780 lb

If we take the 12780 and subtract the truck weight (weighed by itself) of 6920 lbs we get a trailer weight of 5860 lbs.

If we subtract the trailer axle weight of 5060 lbs from the trailer gross weight of 5860 lbs we arrive at a tongue weight of 800 lbs.

If we take the weight lost from the front (380 lbs) and subtract it from the weight gained on the rear (1180 lbs) we again get 800 lbs which is the tongue weight.

800 lb tongue weight divided by the 5860 trailer gross weight equals 13.6% This means that the trailer's actual tongue weight is about 13.6% and this is pretty much spot on the common recommendations of 10% to 15% with 12% or 13% being near perfect.

Charles

 

[F2CMaDMaXX]

Thanks, that's really good info - however for the time being, as i'm not near any cat scales, i want to get a basic measurement from a basic weigh scale nearer to my location.

If i pull past the scale so only the trailer wheels are on it, what weight will that show me? With the WDH disconnected, would that affect the weight it shows?


Also, tongue weight scales worth getting? look like most are around the $120 mark.


(Sorry, this is going way off topic now)

 

[CharlesinGA]

I have edited a couple of times in the past several minutes, so go back and re-read post #87 if for the accurate info.

With a single platform scale like a scrap metal place, yes disconnect the bars, get one total weight of the entire rig, and if they will let you, pull up and just weigh the trailer axles, then, drop the trailer and get a truck alone weight. That gives you enough numbers to work with.

Honestly, a tongue weight scale is good if you have a small tow vehicle such as a SUV and a trailer that is pushing the limits possibly, and every trip is a little different, you need to keep track of the tongue weight.

With a larger rig, the weights and % of tongue weigh won't vary much from trip to trip unless you make some big change such as water in the tank vs no water in the tank. My water tank is all the way aft, and I always travel with full water, so I weigh that way. If I travel with a empty or partial tank I know that I am better off as it will have a heavier tongue weight.

My trailer has a 7500 lb gross weight and almost 3000 lb of cargo carry capacity, PLUS propane, PLUS full fresh water tank, so I never will get close to full gross weight.

 

[F2CMaDMaXX]

I have edited a couple of times in the past several minutes, so go back and re-read if for the accurate info.

Yes that does clear up some of the instructions, thanks, but i can't use a proper weigh station at the moment, so wondered if i could get trailer only weight from a basic weigh scale.

 

[CharlesinGA]

Weight bars connected confuse the issue. they push weight to the front of the truck and also to the trailer axle, so don't bother with weighing unless they are disconnected.

Yes that does clear up some of the instructions, thanks, but i can't use a proper weigh station at the moment, so wondered if i could get trailer only weight from a basic weigh scale.

With a single platform scale like a scrap metal place, yes disconnect the bars, get one total weight of the entire rig, and if they will let you, pull up and just weigh the trailer axles, then, drop the trailer and get a truck alone weight. That gives you enough numbers to work with.

Same as above, total rig weight minus truck alone gives you trailer weight.

Trailer axles alone, subtracted from the total of the entire rig gives you truck and tongue weight, take that and subtract the truck alone from it to get tongue weight.

Add tongue weight to trailer axle weight to get total trailer weight and that should be the same number (trailer weight) you arrived at above (cross checking).

 

[F2CMaDMaXX]

Good to know on disconnecting the bars.

Alright, all makes sense, thank you - so if i just left it hooked up (bars off) but had only the trailer wheels on the scale, what would that show me the weight of?

 

[CharlesinGA]

Well, the weight not including the tongue weight, which is an unknown. Tongue weight is the most critical number, so you know if you are tongue light or tongue heavy or what. Basically the axles carry 85% to 90% of the weight.

The problem with doing the part on, part off the scale is if the road surface is not exactly level with the scale and the trailer changes angle, it skews the weight. We have a scrap metal place that has a long single platform scale, the platform being about 18 inches below surrounding grade level. It has retaining wall on the left and right sides and tapered ramps down into and up out of the scale. If I were to pull thru that and up out of it, leaving the trailer alone on the platform, it would be tilted tongue upward, and the amount of weight measured would be different. By how much I'm not sure.

I used to be heavily involved in the weighing of airliners where I worked. DC-9's, MD-88 &90's, Boeing 727, 737, 757, 767, 777, L-1011. The airplanes had to be level, and if not, the numbers were too far off from the previous weights, which you used for reference. Every airplane had to be weighed every five years. Sometimes we'd weigh only to discover the previous shift had not got all the fuel sumped out of it. The long Douglas models, the MD-88 and 90's were difficult, just get them a tiny hair off, nose high or nose low, by what amounted to an inch or so, and the numbers were useless.

Basically proper tongue weight is a large part of what prevents trailer sway, some are more sensitive than others. Some are ill designed with too much storage aft (like mine) or too much storage aft (like mine), and thankfully I can get away with not using the aft under bed storage as I have a long tongue model with a "cargo pod" on the front of it, and option not all of this model trailer have.

Charles

 

[F2CMaDMaXX]

Alright, all good info, thank you. Sounds like i don't technically need a tongue weight scale, so long as i use the method you detailed here?

 

[DonTom]

Tongue weight is the most critical number, so you know if you are tongue light or tongue heavy or what. Basically the axles carry 85% to 90% of the weight.

I think it's about time for me to ask another dumb question or two . . ,

Since the engine and tranny weigh a ton or so, and both are up front, what is it in the rear that weights so much? Even the driver and passengers are up front. So what is it in the rear that makes an RV so heavy back there?

And does more weight make it significantly more likely to cause a tire to blowout?

-Don- Borrego Springs, CA

 

[Contributor]

Maybe I'm not understanding the purpose of disconnecting/removing the WDH bars for weighting. To me it makes more sense to weight everything connected. The weights gotten are what will be carried by the axles as it travels down the road.

So this is what I would do (everything loaded and connected as you would travel down the road).

1. Drive the tow vehicle front axle unto the scale, get number X
2. Drive the tow vehicle unto the scale but the trailer off, get number Y
3. Drive the tow vehicle off the scale and only the trailer on the scale, get number Z
4. If you can fit, weight all vehicles together for a sanity check.

X is the weight carried by the front axle (includes the tongue weight moved forward by the WDH). If you don't exceed the axle rating then you are good.

Y minus X is the weight carried by the rear axle (includes the remaining tongue weight of the trailer)

Z is what the trailer suspension is carrying. As long as Z is lower than the GVWR, then you are OK

Y plus Z is the combined weight of the tow vehicle and trailer. If it's less than the GCWR of the tow vehicle, then you are golden.

As long as the tow vehicle sits level and no axle rating is exceeded, then you are good.

 

[Larry N.]

Since the engine and tranny weigh a ton or so, and both are up front, what is it in the rear that weights so much?

Do you know where the CG is of your unit? With all the house, appliances, storage, etc. along with water/etc. tanks, even fuel tank, there is a reason they have dual wheels on the rear axle, and a reason that the rear axle has a higher load capacity than the front axle.

FYI, on the 2010 Bounder 33U I used to have the front axle is rated at 7,500 lbs and the rear axle is rated at 14,500 lbs.

 

[DonTom]

With all the house, appliances, storage, etc. along with water/etc. tanks, even fuel tank, there is a reason they have dual wheels on the rear axle, and a reason that the rear axle has a higher load capacity than the front axle.

I just wouldn't think all that stuff would weigh as much as an engine and tranny along with a couple of people (usually) up front.

I don't think they could easily put dual wheels on the front or perhaps they would, in many cases.

I wonder if it would make more sense to have gas and freshwater tank full before having it weighed. Or would half full be better?

-Don- Borrego Springs, CA

 

[CharlesinGA]

Maybe I'm not understanding the purpose of disconnecting/removing the WDH bars for weighting. To me it makes more sense to weight everything connected. The weights gotten are what will be carried by the axles as it travels down the road.

If the bars are left connected, you have no idea how much the trailer or the tow vehicle weigh, or how much the tongue weighs. This can only be determined without the bars connected. You should not be in a situation where you are depending on the bars to relieve axle weight to keep from exceeding the limits.

The traditional way of adjusting the bars is to measure front fender to ground without the trailer connected, then measure with the trailer connected, then tension the bars to take out half of the difference. Some newer vehicle manuals will specify a somewhat different procedure, which you should follow.

You load the trailer for a "correct" tongue weight (10% to 15%), then you connect and adjust the bars. You gotta start at the bottom, and that is without the bars connected.

Thats my take on it.

Charles

 

[CharlesinGA]

I just wouldn't think all that stuff would weigh as much as an engine and tranny along with a couple of people (usually) up front.

I don't think they could easily put dual wheels on the front or perhaps they would, in many cases.

I wonder if it would make more sense to have gas and freshwater tank full before having it weighed. Or would half full be better?

-Don- Borrego Springs, CA

I would weigh in the worst case which is everything full. Part of the reason the rear axle carries so much weight, is that there is so much overhanging it. Its like 3/4 of the RV is sitting on the rear axle. RV's are made from heavy stuff. Wood cabinets, mattresses, water tanks with water, and don't forget the water heater's 6 gallons too, plus batteries, generator, the fridge, etc. The motor and the transmission are really not that heavy in comparison and virtually all of their weight bears on the front wheels. Newer motor homes have taken to stretching the chassis and not having so much overhang. Older MHs had frame extensions on the back to support the body, usually weak and not designed for trailer hitches I might add.

There is a fellow over on iRV2 who has a very nice Phoenix Cruiser. Its about a 2007 model and he special ordered it without a slide. He has a lot of rear overhang. The front is so light, he ended up putting weaker springs in the front, and improved the ride quality a hundred fold.

This is Ron's Flickr page of photos 2007 Phoenix Cruiser 2350

His class C is typical of many, take a look at it and tell me where most of the weight is. (I cannot port a pic over here, so just follow the link to his album and take a look at a side view of his immaculate MH.) If you assume that the weight of the coach is evenly distributed throughout (which it is not) you can see that all of the weight is riding on the rear axle.

Charles