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Friday, May 17, 2019

Do your Tow Vehicle and Trailer match?

Here is some good advice I found on the Interweb and agree with.

Here is a short video from the RV Safety Education Foundation. A longer in-depth video link available at the end of this post.

 You should always do your calculations based on the GVWR of the trailer, not the dry (shipping) weight. The dry weight is a number used by some manufacturers and some dealers to try to sucker people into purchasing a trailer that is too much for their truck

The same goes for tongue weight. The marketing brochure may provide the trailer weight based on the empty trailer (with no propane or batteries, etc.). You should figure your weight based on 15% of the GVWR of the trailer. But the real trailer weighs figure you should know is what the truck scale tells you once the trailer is fully loaded but not hooked to the tow vehicle.

You can not use the "paper" figures found in truck or trailer literature and certainly not the verbal information from the truck or trailer salesperson to calculate your towing capacity. You MUST have real numbers which mean actual scale weights.

Next, take the cargo capacity of your truck (from the payload sticker from the door jamb of the driver's door on the truck). It will say something like "cargo must not exceed ... lbs.". From this payload capacity, you need to be able to deduct all of the following:
- People in the truck
- Cargo in the truck
- Weight of the WD trailer hitch or of the hitch for the 5th wheel
- Total actual weight of the trailer


Then you should also consider the maximum or gross combined weight rating (GCWR) - this is the maximum weight you're allowed to have on the road, which combines the full weight of the truck and trailer combined. To get these, you can use the GVWRs of both the truck and trailer, but really you should go to the scales and have them weighed as YOUR truck and YOUR trailer almost certainly do not weigh what is shown in the literature.

When working all these numbers, you need to consider the following:
- Do I have enough truck (engine, transmission, etc.) to pull this load up and over the hills without causing undue stress on the engine/transmission, etc?
- Do I have enough truck (brakes) to stop this whole load in the event the trailer brakes fail without causing undue stress to the truck brakes?
- Do I have enough truck (suspension, tires, etc.) to control the trailer in heavy winds, while passing or being passed by semi trucks - and especially in the event of an emergency maneuver, like dodging a deer which just jumped out on the road in front of me or a tire failure (blow-out).
I hope you're getting the basic information before you purchase. You'd be way ahead of the game.


In-depth video at RVSEF web site on truck - trailer matching HERE.

##RVT897

Friday, May 10, 2019

Have you "tested" your TPMS?

Like anything mechanical or electrical, parts can die, wear out or malfunction. While I am not aware of a lot of reports of failures of TPM Monitors or sensors I would be surprised if the only problems were related to battery life or improper set-up.

This post is limited to TPMS that use externally mounted sensors. i.e. the ones that screw onto the end of your valve stem.

Batteries. They eventually will die. The early warning of loss of signal from a sensor that previously was working appears to be an occasional intermittent loss of signal, followed eventually by almost constant no signal on the display. This is easy to fix as most of these systems have user replaceable batteries.  I always carry a couple but also I don't stock up as batteries may lose power even sitting in their original packaging.

"O" ring:  Under the screw-on plastic cap there is a very small O-ring. As with any rubber component they can simply die ( crack or tear) just from normal use as rubber does "age-out" due to exposure to heat an Ozone in the atmosphere. I would suggest having a few "O" rings on hand as, unlike the batteries, you can't just pick up a replacement at CVS, Walmart, or Walgreens. You will probably have to get them from your TPMS dealer. When you screw the cap on the sensor don't overtighten the cap as that can distort the O-ring and shorten its life

Plastic cap. This part should last longer than the rubber O-Ring but plastic ages too. Again this is special and unique to your brand TPMS so having at least one on hand from your dealer is a good idea. Also, don't over tighten the cap. It might be possible to seal a cracked cap for a short time with Silicone seal or glue but be careful not to glue the cap to the sensor.

Sensor electronics. All you can do here is get a new replacement sensor. Some brand TPMS offer a longer-term warranty (Lifetime) others only 12 months. I do carry a spare sensor but not in my toolbox or parts box but I added a sensor to my spare tire. in my Class-C. This gives give me a replacement I could use on a ground tire if one of those sensors ever failed. It would only require a quick program change when I move the sensor from a spare position to the ground tire. I could do without a sensor on the spare for the week it might take to get a replacement sensor. The reputable dealers I have talked with all offer single sensor sales or replacement under warranty. A sensor on a spare tire would probably last longer than the other external sensors as it isn't exposed to potential strike from road debris or heat from the tire or brake drum. If I had a sensor fail I would plan on keeping the cap and O-ring if in good condition as a future spare part.

Monitor. Well if this part fails I don't know of any repair a user could do. You just need to get a new monitor from your dealer and hope you have a good warranty and that your dealer will sell the monitor by itself so you don't have to buy another complete system.  I have to admit that I did manage to damage my older monitor after four years of reliable use. I grabbed the wrong power cord and connected it to a 12v source which fried the monitor that only wanted 5V. My Bad. Luckily I was able to get just the sensor and didn't have to buy a bunch of new sensors at the same time.

Replacement parts: If you bought your TPMS from a dealer that specializes in the RV market and attends RV shows then you should be able to get individual parts with little problem. If on the other hand, you purchased mail order from Amazon or eBay or similar, I have no idea what parts or service you can expect.

Testing:  This is something I doubt any have done but after some consideration, I think I have an easy and workable plan.
I suggest at least once every 6 months when you are at a location where you have nice weather and a bit of time you conduct an operation test.
With the system on, I would record all the readings from for both pressure and temperature. With the Co-Pilot in the driver seat, I would go to each tire position and unscrew the sensor. The Co-Pilot should signal the tester as soon as a warning is given on the monitor. You might use your phone or walkie-talkie or maybe a 3rd person, as honking the horn as a signal might become bothersome for your neighbors. If all the sensors give a warning within a few seconds (read your manual on the claimed warning time) all is OK. If there is a delay or no warning after say 10 seconds then there may be a problem in either the sensor or monitor or programming and you MUST learn the why and take corrective action as you are depending on receiving prompt warning of air loss.
You can also use this opportunity to confirm your cold tire pressure with your calibrated hand gauge. (See THIS post on how to confirm your gauge is sufficiently accurate) and you can also "top-off your cold pressure with your normal margin of air.

##RVT896

Friday, May 3, 2019

Expected tire life

I Saw a question on tire life:
"I was wondering could some one cover a topic travel trailers ,5th wheel, bus , semi's and semi trailers, and anything recreational  W H A T   IS   T I R E   LIFE  FOR  THEM?  I have never seen this covered   HUM !"
I have covered this in a few different posts on this blog and some RV forums but this post may put it all in one place:
Generally, tire life for Bus and HD truck is based on wear, not time, as these vehicles may drive 50 to 100,000 miles a year with the tires wearing out at 50 to 80,000 miles.
Daily drivers (cars  & P/U) drive about 12,000 a year and may get 3 to 5 years life again most based on wearing out.

With RVs (Trailer & Motorhome) mileage might be as low as a few hundred miles a year to a few driving up to 20,000.  BUT if you consult your owner's manuals you will probably see them point out expected life to be 3 to 5 on trailers. Motorhomes probably hit 7 to the suggested max of 10 years, again before wear-out due to low miles driven in most cases.

 The primary reason for the earlier "end of life" on trailers is the result of the unique radial belt shear forces identified in this blog and in the industry technical papers as "Interply Shear" that comes from a combination of tires being dragged rather than steered around corners and tires "fighting" each other when going around corners as the tires on different axles are not all rotating around the same center of the turn. It is the Interply Shear that initiates the cracks between the belts and accelerated the crack growth that can end up as a belt separation before the tires wear out. The Interply Shear damage is augmented by damage from improper (low) inflation, improper (high) load and in some cases, excess heat due to speeds higher than the basic design called for.

 I hope this helps others why we have different tire life experiences on our RVs than with our cars.

##RVT895