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Friday, May 29, 2020

Are your "Nuts" tight enough? Part 2

This topic of how to ensure your Lug Nuts are tight enough, but no too tight,  is a two-parter and this is Part 2.

The first part, if you missed it, covered the Science and Engineering behind the basics as I am expecting that there will be a number of people who will say something along the lines of "Roger, You are all wet. I've done it THIS way for years and never had a problem".

You are certainly welcome to ignore my advice and continue with the methods you have used for years. My target audience is those who are still new to the RV life and do not have years of automotive or mechanical background or training, and those that want to ensure they do not end up with a wheel coming off their RV or breaking a wheel stud.

OK let's jump in.

I am confident that no one wants a wheel of their car, RV, trailer, or dolly to come off while traveling down the road as seen in THIS video. Or maybe even worst to cause someone personal injury as seen HERE. (The man suffered a fractured skull and chest injuries). So what do we all need to do to prevent a wheel coming off one of our vehicles? It's easy. Just make sure all your lugs nuts are properly tightened and neither the wheel or nuts or studs have been previously damaged. Sounds simple enough but how do we do that?

First, you need to know how tight the nuts are supposed to be. This information should be in your Owner's Manual 

You can check out this YouTube How to Tighten "Nuts" - The Right Way. Note: I covered the sequence for setting or checking the torque depending on how many lugs you have on your vehicle in THIS blog post. One important point to consider. If you had service on your brakes or tires and someone else tightened the lug nuts how do you know they did the job correctly? Many of us have heard about or experienced an over tight lug nut so I recommend you set the torque your self as seen in the video. Then when you are doing the recommended "Torque Check" at 50, 100, and 150 miles you will know that you don't have a nut that is significantly over tight. Note if your owner's manual has different mileage for torque check follow your owner manual. If you find a nut that turns after the 2nd check keep an eye on it in the 3rd check and if still turning you need service as something is wrong.

Let's review the tools you will need and seen in the video.
Remember this info is aimed at owners of RVs with tires smaller than 19.5"So if you are in a Class-A you can read to understand what is happening to your "baby" when you call the service truck.

Torque wrench, 6 point socket of the correct size for your nuts, 2' "Breaker bar", 12" long 1/2" drive extension to allow you to get to your dual wheel nuts. Note Trailer owners may not need this tool.
You will probably not need to use these tools too often so top quality (expensive) is not needed so in those cases I head for Harbor Freight for low-cost tools.
Check these links:
1/2" Drive Torque Wrench. Harbor Freight    or  Lowes

1/2" drive extension     Harbor Freight   or Lowes

6 point "Impact" rated socket I recommend you not use a "12 point" socket as they are more likely to spin off or round off your nuts. You do not need to buy a set. You might want to confirm the size by borrowing a socked from a friend or fellow RV owner. Example 13/16"  Lowes
Note it might be better to go to Lowes or similar as you do not need a set, but be sure to get the correct size not something close enough or you can damage the lug nuts. Here is a 3/4" socket from Lowes.

Now how do you get the tight nut off? a 2' long Breaker Bar will make the job easier. This is what I use. and I can easily generate 200 Ft-Lb

OK so with all the tools you may need collected, How do you set your clicker torque wrench to the spec for your vehicle,
Here is a YouTube to help those who have never used a Torque Wrench.

Hope this helps and if these couple of posts help a few RV owners avoid problems we will be happy.


Friday, May 22, 2020

Lug nut Torque? Why is it important and why measure the force? Part 1

Here are some YouTube videos on the topic of Torque". What it is and how do we measure the force. As an engineer, I sometimes just assume that everyone understands some basic Engineering terms but I am wrong to make that assumption. You don't have to remember all the details. I am just hoping that when we are done with this topic you will accept our recommendations on how to set and how to check the torque of your lug nuts.

Important info. It is impossible for me to know the size lug nut or specification for every vehicle but you, the owner should know this important spec and it should be in your owner's manual. If you can't find it, find a dealer of your brand RV or check the on-line forums for other owners of your exact make and model and ask what the specs are. These numbers are critical for the safe operation of your vehicle. I can only talk in generalities in this blog.

One thing to remember is that for Class-C and Class-B RV motorhomes and for RV trailers as with your car or pick-up with 14" to 16" steel wheels, the torque spec is probably between 75 Ft-Lb and 85 Ft-Lb, while 19.5 tires run about 135-145  and 22.5 tires run 450-500 Ft-Lbs. So you folks with large wheels will have to depend on the service truck to tighten your lug nuts. It is possible to get a hand torque wrench with 1/2" drive sockets that will get you to the 150# to 200# range, but it is probably safer for you to leave the larger wheels and lug nuts for the service tech that has the proper tools. I will address the tools you need next week.

Here is a video that explains what torque is?

Friction is the next topic.

For proper torque of our lug nuts, the stud and nut need to be clean, rust-free, no damaged threads, and no oil lubrication unless specifically specified in your owner's manual. If you have had problems with a stud or nut, such as a nut coming off, or broken stud, or the wheel being partially loose or the threads have been cross threaded or the nut was significantly over-tightened, both the stud and nut should be replaced. Over-tightening can get the stud into the "yield" load range which can lead to incorrect tightening and even to stud failure.

This video shows why nuts come apart
"Transverse vibration" is what happens with a wheel is fastened to a hub. This is why we need to check torque to be sure the assembly is retaining it's clamping load after we start driving.

Tensile strength is covered in THIS video.

HERE we learn about SHEAR

Ok, enough "Engineer speak". This stuff is what we engineers learn and use when designing joint and developing specifications for studs and lug nuts. There is no test in my blog on this topic, but if you are going to argue with an engineer, then you will need a solid understanding of these forces.

Now the next step is for you to do a little research
A. Find your owner's manual and look up the specifications for each of your vehicles.
B. Make a note of the torque spec and lug nut size where it is easy to find. A permanent marker on your door jam might be a convenient location.

Ok here is a short video on using s "Clicker" type torque wrench.
We will cover this tool and some others next week.

Stay Safe

You can check out this "entertaining" YouTube from a guy in Australia on How to Tighten "Nuts" - The Right Way

Friday, May 15, 2020

Was your "Blowout" caused by parking at Quartzsite two years ago?

This is a bit of a continuation on the topic of "tire Dressing" from last week's post.
I do wonder how many that complain of sidewall cracking or less than desirable tire durability makes the effort to protect their tires from the heat and UV degradation from direct sun exposure.
While there might be some benefit and shielding from applying such as "Dressing" or "Shine" or other "stuff" to the tire sidewall for UV shielding. No dressing will protect a tire from the accelerated aging process due to being "baked" by the sun's heat.

There is no standard SPF for tire dressings as there is for sun-tan lotion, It would not be that difficult to measure the level of UV shielding by measuring the UV going through some clear plastic sheeting and then applying the tire dressing to the sheeting and measuring the level of reduction if any in UV rays.

In many cases, the rubbing of the tire sidewall when applying a dressing can remove the special anti-oxidants and UV protection provided by the chemicals the tire companies use in all tires.
All rubber, natural or synthetic, loses strength and gets stiff over time. The rate of degradation is also temperature-dependent with the rate effectively doubling with each increase of 18° F. As I have shown in my blog on the use of tire covers sunlight can easily accelerate the rubber degradation by 4 times with 8 times not unreasonable in Southern states. This loss of strength and flexibility can eventually lead to a belt separation, which many sometimes call a "blowout". Maybe that unexplained "blowout" in June was brought about by the eight months of direct sun exposure in Quartzsite, AZ, over the last two winters.

I have confirmed, with temperature measurements, the significant temperature drop with the use of white vinyl covers on Class-B, Class-C and RV Trailer sizes, and the use of a flat mesh "Tire Shades" on Class-A motorhomes. I would recommend against the use of black or dark color solid vinyl covers as they would act more like an oven by both transferring the sun's heat to the tire and preventing cooling air circulation around the tire.


Friday, May 8, 2020

Tire "Dressing" and "do not use covers"! Where's the test data?

Been following a long thread on an RV Forum on the topic of "Tire Dressing" aka tire treatment or "Tire Shine".
The good news is that most posters knew to not use any product that contains Petroleum Distillate. Too bad some RV dealers don't follow the guidelines on this. I have seen a number of display coaches almost dripping with some slippery fluid. Might be Brake Fluid or even motor oil as the tires were shiny and I could scrape the coating off, leaving a "slimy" substance on my finger.

I saw a number of different products mentioned and many suggestions that a product called 303 was a good UV protectant.

I saw no one provide any actual direct comparison test data for any product that would support the claim of protection against UV damage. With a little work getting through the maze of retailers selling "303" I finally made contact with their customer service. I asked "Can you provide any test data on 303 vs other tire protection products. Also info on if 303 application removes any of the wax or oil or anti-ozone chemicals built into tires." The answer was that they would ask their chemists. This seems strange that a company making claims on the performance of their product would not have comparison data available that would back up and support the claim. Please note, I am not saying that 303 does not offer some "protection" against UV damage to tires. I am concerned that the actual application as seen on YouTube may be removing the special waxes and anti-ozinate chemicals tire companies put in our tires.

If I receive actual test data that compares 303 against other products that make similar claims I will post on this blog.

What was most concerning were a couple of posts where the writers claimed
"I got tired of reading all the opinions on tire dressing so went to the source, Michelin. They stated that washing tires with mild soap is the only thing they support on their tires, no dressing no covers, no nothing. You don't see shiny tires at a truck stop and these are the people who put on the miles."
Another said "Goodyear RV tire guide says. Just keep them clean, no dressings, no covers, zip. You can use the same stuff you wash your RV with perhaps use a medium brush on stubborn spots."

I responded:   Interesting comment on "no covers". Wonder what Goodyear RV guide you are looking at? 
I found in THIS Goodyear RV Tire Guide and under storage the advice to store tires "in sunless area" and "Don't store tires where they are subjected to direct sunlight or extreme temperatures".
Based on the above, how does telling us to not use tire covers make sense?
I have confirmed with actual test data that covering tires can reduce the tire temperature by about 40° F which could extent tire life by many months, depending on how long you protect them from artificial heat aging.

I checked and found just the opposite on the shielding from the Sun. In fact I even contacted an Engineer at Michelin and he said "Our position regarding tire dressing and protection has not changed. It is still recommended that tires are cleaned with a mild detergent and water, and they are protected from direct sunlight when the vehicle is parked for extended periods of time. This is usually accomplished with the use of some type of cover. "

So I don't know where the "no cover" info from either Goodyear or Michelin comes from and if you read my blog you know that this tire design engineer is a strong proponent of using White vinyl on Class-B & C tires and the flat mesh of any color on Class-A.

I have nothing against 303. I am wondering why, for the price they don't have any actual direct comparison performance data on UV protection.

PS. If you don't want to protect your tires from the heat aging due to sun exposure please don't ask me to explain why you don't get longer life from your tires. Also next time you run into someone selling an brand  "Tire Dressing" ask to see the test data and see what happens.

Friday, May 1, 2020

Is Moisture in tires a bad thing. Why with RVs?

The question of Nitrogen being used to inflate a tire has been covered in a few of my blog posts and on some other posts on the internet. It is often mentioned that the Nitrogen used to inflate tires is "dry" and so that is considered a positive but I don't recall anyone getting too specific on why "dry" is better than "wet". Before we get into that part of the discussion I want to be sure that everyone understands that any "gas" you buy in a high-pressure tank aka cylinder, will be "dry" as the process of separating the gas and compressing it removes the moisture. So if you were to buy a cylinder of CO2 or Argon or Helium etc the gas would be "dry.
I did a post in May 2012 as one of my early posts on How to get dry air for your tires by making your own air "dryer" for less than $20 for an almost endless supply any time you need it.
There are some companies that sell small cylinders of various gasses but you would also need to have a pressure regulator and a source of high pressure (1,000 to 2,000 psi) gas to refill your tank.

But back to the original question of why do we want to keep moisture out of our tires and why would getting "dry" or at least "dryer" air for our RV tires be advisable. By "Dryer" I am referring to the wet air you can get out of the "free" air at some gas stations where they might not maintain their air compressor or air dryer.

In the past when RV trailers came on Bias or tube-type tires we didn't worry too much about dry air primarily because the tube did a pretty good job of keeping high-pressure moisture out of the tire carcass plus those bias tires did not have steel belts and were probably just Nylon or Rayon cord.

The modern radials we use today are almost all "Steel Belted Radials". So the question is what happens when you "mix" steel and water?  The steel can rust over time. Now in most tires on your car or TV you may drive it almost every day. The driving generates heat and this heat is highest at the belt edge which would be the most susceptible to moisture. This heat tends to drive the moisture out of the tire rubber. However, if you let the tire sit for days or weeks moisture in the air can migrate into the tire structure. Moist inflation air can be driven into the tire structure and over time this moisture can attack the ends of the steel belts and form iron oxide. Rubber doesn't stick very well to the rusty steel so tears can initiate at the molecular level. Once cracks or tears are initiated in a tire they can only grow and if allowed to grow long enough or big enough you can end up with a separation in the tire structure.
Keeping moisture out of the rubber structure is why we also recommend you not park with your tires on wet sand or dirt and the moisture can migrate into the structure if exposed to water for weeks at a time.
Please don't jump to conclusions and say "Ya but I drive in the rain" or "Occasionally it rains and my tires get wet".  I am not talking about a few hours of exposure or even a few days. If you drive and heat up the tires it will drive the excess moisture out of the tire. It is weeks or even months of parking in a wet situation that we want to avoid.
Not inflating your tires with wet air (if you get water drops spitting out of the air hose it is way too wet to use except in an emergency) is what we would like to do. If you remove your valve core and what looks like fog or steam or water droplets spits out you have too much water in your tires and this is under high pressure all the time so this can affect the life of your tires.

Many after market tire sealants are water based so using that stuff can hurt your tires.

So that is why inflating your tires with dry or at least drier air is a good practice.