Tire Temperature & Pressure - A Hot Topic"Today's key fact: Check your tire pressure in the morning, before you drive and before the tire gets warmed by the sun.
Now the background information for detail oriented:
The general guide for checking tire inflation is to do it when the tire is "cold". In this case "cold" means the tire is at the same temperature as the air and not in direct sunlight as the sun can raise tire temperature by 10°F to 50°F. The tire also needs to cool down after being driven and the rule of thumb is to wait at least two hours after driving.
Another rule of thumb relating to pressure change due to temperature change is that for a 10°F change in the temperature the pressure will change by 2% so for your big Class-A tires that means about 2 psi for each 10 degrees while on your passenger car you can figure about 1 psi for each 10 degrees. If you remember these numbers you don't need to do the math.
All of these numbers are based on the "Ideal Gas Law" and the assumption that the tire does not change volume. Both of these assumptions are valid unless you are trying to measure tire pressure to the nearest 0.1 psi which even I didn't do on my race car.
All this variation and "Rules of Thumb" are why I and others suggest you run your passenger tires (35 psi max) about +3psi, Your Light Truck tires ( 65 to 80 psi max) at + 5 psi and your Class-A size tires ( 100 - 120 psi max) at + 10 psi from recommended minimum. With these extra margins you don't have to worry about a few degrees temperature change or the one to three psi per month you will normally loose.
More about some troublesome tires:
"We have a Keystone Laredo which came with Mission tires. Within three days we had two tires fail. One had a bubble and the other blew out five miles from home while heading to the mountains. It did damage the trailer. Tireco, (the parent company), will not cover the damage. They say the tire that blew had impact/road hazard damage. I don't believe this at all. We had 50% of the tires go bad on this RV in three days. They did pay for the bubbled tire. I see on the web that there are numerous complaints regarding these tires. Can you, or any reader give me information on these tires, or what recourse we have?" Louise C.
"Sorry to hear about your problems with the Mission tires Louise; you evidently are not alone. Check the size of your tires and see if they are on the formal Recall notice. There have been many reported problems with these imported tires; the blogs of full of comments regarding them. Here’s an article that was posted back in 2007 that you might find interesting.
According to some, it simply is not worth the risk to continue using a Mission tire. Most have simply switched to one of the better made US tires and have not looked back. I’ve not heard many positive comments regarding Tireco as well.
I wish I had better news for you, but from a safety perspective, it would be wise to simply replace all the Mission tires with a US-made tire. From my research, it is much better to be safe and absorb the cost than to risk damage or injury. If possible, save and store the old tires in case an opportunity for a rebate or refund becomes a reality.
Also, understand how vital it is to know the true weight each tire is actually carrying! Individual weight measurements taken at each tire position, using a certified scale, is the only, I repeat, the only way to know how much to inflate each tire. It's also the only way to know if an axle is overloaded to one side.
The most common cause of tire failure in the RV industry is a combination of under-inflation and overloading.
You must weigh it to know it! Regardless of the brand of tire."
Light Truck tires on trailerHad a question from a reader:
"I am, frankly, baffled about what to do about our tire situation. In this instance, our tire that went flat definitely was not overinflated. It had been checked about two days prior and had 63 pounds. We have been running nitrogen since the tires were put on and have not lost a pound in any of them in 3 months.
When we upgraded to 80 pound, E-rated tires three years ago, I asked about the rims' ability to hold that pressure. Stupidly, I took the tire dealer's word for it. In 2008, we started blowing Denman tires all over Montana: three of four blew, tires with about 8,000 miles on them.
On our way to Maine in May, we blew yet another tire and sought advice from the guy who owns the campground where we were headed. He is a tire dealer, and advised us to go back to the original equipment 65-pounders, which we did. Now, we have a rim problem.
An 80-pound Maxxis, which we kept as a spare, is now on the trailer. The one that went flat will be on a new rim and used as a spare until we get home. Clearly, we had lost pressure in that tire before we got to the CG; how much is the question. It was not flat or we would have noticed it when we put the chock between the wheels. That tire will undoubtedly go bye-bye when we get home.
I will research rims. It sounds like I should replace all rims with ones that are capable of handling E-rated tires if we want to go that route again. I do not think we have room to upgrade to 16-inch wheels, but I now am going to find out for sure. If it's possible, we will do that.
I am adamant about checking tire pressure, so I am confident we have not been running on over or underinflated tires. We are not overweight, and our axels are fine.
It is obvious we are doing something wrong. I'm beginning to feel like we are too stupid to own this 5er! Hope your eyes don't glaze over reading all this...thanks for your input."
Answer "You didn't mention if you ran 65psi or 80 psi in your "80 pound" tires. I wonder if you are running metal valves, as standard rubber valves are not rated for more than 65 psi. Also the rims have a max load and max inflation rating. Did you check the rim stamping?
You also were not clear if you were running LT or Light Truck tires or had been running ST or Special Trailer tires. These two different type tires have different load ratings even if the rest of the numbers were the same. A LT235/75R16 Load Range E has a different rating than an ST235/75R16 Load Range E.
An "80 pound" Load Range E tire rated for 80psi will carry no more than a Load Range D tire will if they are both inflated to 65psi. It is the air (nitrogen) that does the work and carries the load not the tire. Just because you checked the tire two days earlier is no guaranty you didn't get a nail as you left the CG that day and drove for two days on a leaking tire. This is one of the best arguments in favor of TPMS.
With all the tire failures I have to ask what your real (not sticker or guess) axle by axle side to side loads are when you are fully loaded going down the road. With those numbers you can consult the manufacturer’s charts.
While you are getting the TT weighed it won't hurt to get the four corner weights of your tow vehicle too.
One thing few realize, including the tire salesman, is that according to Industry Guidelines LT tires require an inflation increase or even a load reduction if you ever drive over 65mph. ST tires also have a speed restriction that needs to be considered.
The only way to know if this is not needed is to consult printed literature for your brand and design tire from the tire manufacturer. I would not assume the tire salesperson knows the correct answer. "
Should you "plug" your tire?This is a very important post. Improper repair can lead to a false sense of security and even to a tire failure which can cause damage or even injury. Please read this entire post. http://www.rvtiresafety.com/2011/05/should-you-plug-your-tire.html
Weighing your rig for safety:
Question: What is the number one cause of RV insurance claims? Answer: Blown tires.
"A big motorhome tire may cost $650 to replace; the damage caused by that blown tire can run into thousands. Sadly, a leading cause of blown RV tires is overloading--a problem that can resolved before the blowout. We've often commented on the importance of not overloading a rig. But how do you go about knowing your weight?
Walter Cannon is the executive director of RVSEF, a nonprofit foundation that provides RV safety education training at RV shows and seminars around the country. Cannon says that ideally RVers should know their individual wheel (tire) weights. Why so? Take a motorhome that rolls onto a platform scale at a truck stop. Let's say the axle scales in at 10,000 pounds. To then "think" that must mean 5,000 pounds per wheel could be a mistake: There could easily be 4,000 pounds on one side of the axle, and the other 6,000 pounds on the other side.
If the tires on the rig are safe for a maximum load of 5,000 pounds each, a disaster is simply waiting to happen." By Russ and Tina DeMaris
Read the rest of the article at: http://rvtravel.com/RVusing/Weighing_your_rig_for_safey.shtml
Ed and Marilyn have posted pictures of their burned up 5er:
http://www.mytripjournal.com/travel-607759 How terrible, and all over a suspect wheel bearing.
The rain was so welcome, and cooled the temperatures down so much that I had the doors and windows open, as it wasn't a driving rain. Prime and Bobcat spent most of the day on the screen porch, whereas before they could only stay out there from about 6.00AM to 8.00.AM. For the first time in their little lives, the kittens could smell fresh air at their open window in the Grooming room. They had been in heat or air conditioning all this time.
The rain caused concern for Misty, she didn't want to get wet. Paco knows that when it's raining, he has permission to pee on side of the walkway that is under cover, instead of going all the way to the back yard. He hates rain, whereas he loves to sit out in the sun.
Old Misty forgot this "rain rule", as it has been 148 days since we had any rain, so she wouldn't pee by the covered part of the pathway. So I blocked her from coming back to the front door, and kept on telling her to "Go Pee", as I knew she had to go. Eventually, she went sloshing through the water to the back yard, and pee'd.
Now, I had a wet dog on my hands, so she had a bath, (rather, shower) in the little bathroom which is off the Middle room.
The kittens were loose in the Middle room, so they went into the bathroom while I was bathing Misty. They follow me to see what I am up to, and 'help' me. They got in the trash, knocked over the doggie shampoo bottles, 'killed' the mop, and had a right old time. They had never been in there before, as I was scared one might drown in the toilet, so I always keep the door closed.
Then they purred up to Misty while I was brush-drying her, she didn't know what to think of that. These kittens are getting a well rounded socialization.
According to the weather station across the road, we got 1.23" of rain, so it didn't take long for everything to green up today.