A couple more newby questions!

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wijames2002

Well-known member
Joined
Sep 28, 2017
Posts
168
Location
Tavares, FL
Just a couple of things I've been wondering about
1  How do you know if you have a flat on the inside rear tire?
2  I see I have a deep cycle battery as my cranking battery. Is that how it should be? and is the cranking battery charged by shore power or only when the engine is running?

Thanks
 
The only real way to know the air pressure on your inside tires is to check them with a gauge.  There will be a tire steam inside one of your outside wheel holes.  The steam maybe deep inside so it may be difficult to find and almost impossible to use but you can install an extension on them which will make it very easy.

Some do and some don't use deep cycle batteries for the engine, I do not.  In most cases the engine battery will stay charged when you are attached to shore power or use your generator through the inverter/converter.  If yours does not you can simply add a battery tender/minder plugged into one of your coach outlets.  Many RV's have an outlet in one of the basement compartments that can be used for this.
 
On the inner duals, it's very helpful if valve extenders are installed. They extend the valve stems of the inner duals, so you can access them with a tire gauge at the outer duals. Another great idea is to install TPMS sensors on the valve stems of each tire. The sensors transmit tire pressure and temperature information to a receiver in the driver's compartment, which alerts you to pressure losses and tire over-temp conditions while driving.

A deep cycle battery will work as a chassis (engine-starting) battery, but they're not ideal. Deep cycle batteries are better suited as house batteries, because true deep cycle batteries are capable of repeated deep discharges over longer periods of time, without being damaged (Up to a point.) Batteries that can discharge their amperage quickly are better suited as chassis batteries, because the starting process can require a lot of amperage in a relatively short period of time.

Kev
 
I guess I should re-phrase my question. If you're going down the road and have a flat on the inside rear, are you going to know it or only when you check the pressures?

Thanks
 
If you are going down the road and one of your inside rear tires goes flat and it stays intact, unless you are driving heavy (really heavy) you most likely will not know it until you check it or it comes apart.
 
A trucker's trick is to take a billy club or a mallet and individually thump the treads on each tire.  A tire that's low or flat will cause a distinctly different sound and rebound of the stick than one that's properly inflated.
 
Going down the road, the only way you are going to know if if you have a TPMS. Until the flat tires blows or self-destructs due to overheating, that is. Then the flying rubber may catch your attention in the die view mirror. Or the loud bang when the flying tread tears into the side of the motorhome...
 
Lou Schneider said:
A trucker's trick is to take a billy club or a mallet and individually thump the treads on each tire.  A tire that's low or flat will cause a distinctly different sound and rebound of the stick than one that's properly inflated.

While "thumping" a tire will indicate a very low or flat tire, it's not a very accurate way of determining a tire that's up to 30% or so low. One of the major truck tire company's used to sponsor contests at various truckers rodeos where people could attempt to pick the low tire in a pair by thumping them. The pressure difference was 40 PSI as I recall, although I don't recall what the tire sizes were. In their published results covering about 100 of those contests, the correct tire was chosen only about 35% of the time, and a fair number of the correct contestants admitted they had just guessed when the thump test wasn't conclusive. As said, a TPMS is the more reliable choice.
 
The thump test was never intended to spot tires with somewhat low pressure.  It's basically a way to detect a completely deflated tire in a dual pair, where the good tire is carrying the entire load and thus the deflated tire therefore does not appear "flat".  In that scenario, there will be a noticeable sound difference between the two tires in the pair. It won't, however, help you determine if both tires are a little low, or even if a single tire is 10-20% high or low. And 10% has a significant effect on tire wear, tire life, and fuel economy.

The bottom line is that a odd-sounding thump can warn you to get out the tire gauge, but a seemingly good thump doesn't prove anything.

I always liked this quote:

?When I see a truck driver walking around thumping their tires, I tell them they might as well take that stick and whack the hood of their truck to see if it needs oil,? says Harvey Brodsky, managing director of the Retread Tire Association. ?That?s how accurate a tire thumper is.?
 
I've lost an inside tire twice while underway in our average weighted class c. For me there was no guess work. Both times I could instinctively feel that I needed to slow way down and get myself off the road. Same thing in a 6 wheeler box truck when I was a kid. When you've lost an inner or an outer tire in a vehicle you are driving you know it. Low pressure is unnoticeable but a flat is a flat and my experience is you feel it and know it.
 
Gary RV_Wizard said:
The thump test was never intended to spot tires with somewhat low pressure.  It's basically a way to detect a completely deflated tire in a dual pair, where the good tire is carrying the entire load and thus the deflated tire therefore does not appear "flat".  In that scenario, there will be a noticeable sound difference between the two tires in the pair. It won't, however, help you determine if both tires are a little low, or even if a single tire is 10-20% high or low. And 10% has a significant effect on tire wear, tire life, and fuel economy.

The bottom line is that a odd-sounding thump can warn you to get out the tire gauge, but a seemingly good thump doesn't prove anything.

I always liked this quote:

Exactly, yet many truck drivers believe they can tell the pressure by the "thump" tone. I've even seen them thumping steer tires.

Yep, I like Harvey's quote too!
 
Spend the bucks and get a Tire Pressure Monitor System.  It will tell you when there are problems and mine even tells me there are problems when there are none ( a few times).

Battery:  A lot of coaches have the engine battery charged only by the alternator when the engine is running.  The house batteries are charged by the generator or shore power.  A little device called Trik-L-Start allows the engine battery to be charged from the same charge going into the house battery when on generator or shore power.  No plug in is needed for the Trik-L-Start.

Bill
 
MedfordRV said:
I've lost an inside tire twice while underway in our average weighted class c. For me there was no guess work. Both times I could instinctively feel that I needed to slow way down and get myself off the road.

This is what I would think... the rig is going to perform/track differently once a rear tire fails.  If the driver is paying attention to how the rig feels (which is pretty much required with RV driving), you ought to know.

When I blew my outside dually on my motorhome, the tread separated and the tire's steel belts underneath were whipping around and whacking the tailpipe on every rotation.  It was the most horrible metal-on-metal sound I've ever heard, like 1000 spoons being tossed into an industrial sized garbage disposal!  Luckily the tailpipe was able to be bent back to its correct position, and my rig's underbody suffered no significant damage.
 
If a tire's pressure is down 30% or so, it will run hotter. A hand held remote temp sensor should give a quick idea of a problem, takes only a minute or so to go all the way around and check temps. You will soon learn what they normally run temp wise, and though not as precise as a pressure check,or as good as a TPMS,  at least stands a chance of being done often.

 
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