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Wednesday, November 28, 2012

Should you carry a spare tire in your RV?

Here is a video I recorded at the 2012 FMCA national rally in Indianapolis for and its daily newsletter RV Daily Tips.

Wednesday, November 21, 2012

Long Term Parking - Winterizing

Now is the time many RV owners are "winterizing" their RV. Even if you are in Arizona, you might be getting it ready to be parked for many weeks or months. There are a few things you need to do to help preserve your tires.

1. When you wash your RV prior to storage be sure to clean the tires. The easiest thing to do is to treat your tires just as you would the side of your RV. Wash the tires with the same soap & water you use on the RV body. You wouldn't use SOS pad on the bodywork so don't use coarse scrubbing material on the tire.

2. Inflate to the pressure shown on the tire sidewall. This will decrease the tendency to flat-spot and make the tire flat on one side.

When I was checking the inflation I discovered one tire was almost 30 psi low. I knew the tire had not lost air when it was being driven so I immediately suspected that when I removed my external TPMS sensor the valve core must not have properly seated. This was confirmed with a shot of household cleaner. Here you can see the small bubbles that confirmed the 3.5 psi per week air loss past the valve .

3. If you are not parking on a concrete floor or pad it is suggested you not park on ashpault as the oils in the tar can attack the tread rubber. It is also suggested that you not park on dirt or sand as the moisture can migrate into the tire and possibly cause corrosion of the steel.
I have some pressure treated board that are large enough to completely support the contact footprint.

Here you can see the board and the reference footprint for a front tire.

You always need to completely support the entire footprint. Both in length and width. These pictures show what NOT TO DO.
                                                                                Too narrow

Off center

                                                                                             Just Right

 Be sure the support is wide enough for both duals.

Finally be sure to cover the tires to protect them from direct sunlight which can cause UV damage and overheat the tires.

If you haven't read my series on Tire Covers simply check "Tire Covers" on the label list to the right.

A little bit of preventive care can help avoid future problems and extend the life of your tires.

PS Don't forget that even when parked you should check the air pressure once a month. If I hadn't checked the air in the tire with the leaking valve it probably would have been flat by next spring and might even have been damaged and unsutable for highway use.

Wednesday, November 7, 2012

Valve extensions

A review of some of the various RV forums will reveal that a fair portion of people have had some form of problems with valves and valve extensions. One poster provided a nice option that worked for him.

Jake L. from South Carolina had problems with getting his pressure gauge and inflation chuck onto his valve stem through the openings in his rim & hubcap.

Jake had some 135 degree stems installed but the company doing the work apparently did not do the work correctly and his new stems leaked. He now has regular straight stems that don't leak but he can't get the double foot chuck to work.
His solution was to use short extensions some call "Alligator". Here is a picture of the short extender.

Note the nice metal valve cap. Some people incorrectly believe that the "Alligator" cap is an acceptable alternative to a regular cap as it allows you inflate or check the air pressure through a small "trap door". The problem with using the cap in this manner is that it will allow dirt and grit to enter the valve stem chamber.           

I covered the topic of dirt in the valve core 11/2/12. Check it out if you haven't already read it..

Here you can see that this short extension solved Jake's problems. 

Regarding the issue of keeping dirt and grit out of the valve core chamber, I think this is something very few ever think about.

 My short extension even carries the brand name "Alligator.
 This is what the end of the Alligator extension looks like.

Here you can see how the extension works.

This part should not be considered a cap but just a very short valve extension.

It would be very easy for the end of the Alligator cap/extension to collect dirt which would be blown into the valve core area so if you use an "alligator" short extension be sure to use a cap or screw on TPM sensor

Saturday, November 3, 2012

Quick post with Real Weight numbers

Just got these numbers from a 5th wheel owner
Trailer R Front  3,230
Trailer R Rear   3,185
Trailer L Front  2,840
Trailer L Rear   2,780

If the owner did what many do if they bother to weigh their trailer he would simply assume 50/50 axle to axle and 50/50 side to side. With that calculation he would believe his tire load was 3009 but he would be wrong by 7.4%. This may not sound like much but many RVs are operating with less margine than this.

 This is a real life example of why "tire guys," myself included, tell you to get the load on each corner of your RV an not just a single weight and then dividing by 4 (or 6)

Friday, November 2, 2012

Why do tire valves leak?

Many people who experience a tire blowout insist they had checked their tire pressure and that their gauge was accurate. So they blame the failure on a defective tire. However, what could have been the culprit was a bad cap on their valve.

Now I must say that if you have a TPM sensor that is basically a screw on valve cap, this warning probably does not apply as long as you ensure the valve stem is not dirty or covered in mud when you remove or install the TPM sensor.

A good valve cap is metal and has a small gasket or O-ring in it to seal against the end of the valve stem. The cap serves two functions. Primary is to keep dirt out. Second is to be a backup to keeping the air in if the valve core develops a leak. A cheap plastic cap may work on a 30psi passenger tire but I doubt it will last too long on a hot high pressure Class-A TBR tire.

Lets take a close look at the valve core.

I have labeled the plunger that opens the valve to let air in or out "P". The gasket that seals the core inside the valve stem "S". Note the small indentation that indicates this core has been used but not over tightened.

Finally the location that opens when you press on the plunger "V" is a small circular opening.

To the right is a graphic from Wikipedia showing how a Schrader valve operates.

If you look closely you can see the valve opening letting the air out.

Now lets look at what can happen if you get a single piece of grit stuck in the valve area.

I included the head of a straight pin so you can see just how small that bit of dirt is.

Now lets see what happens if this valve core with the grit in the valve is used on a tire.
Now you see why using a good valve cap is important. You must keep the dirt out of the valve area. If you discover a leak as shown in the picture above, cranking down on the core will only damage the core seal (the black band in the pictures above) and will do nothing to stop the leak. It is best to simply replace the core with a new one.