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Wednesday, January 23, 2013

What valve should you use?

We have discussed valves previously but this time I want to give you some facts and numbers to help you buy the correct valve for your application.

Basically there are two criteria you have to get right. The size hole in the wheel and the cold pressure spec for the tire inflation.

For passenger and light truck wheels that use the standard "snap-in" rubber valves, you will usually find them to be either 0.445 to 0.461" or 0.618 to 0.633" dia hole. There is also a maximum metal thickness of 0.156" at the hole. Some aluminum wheels have special step machining to cut the thickness down to the proper dimension. Most steel wheels do not have this problem as they are thinner than 0.156" and run closer to 0.070". These "snap-in" have a 65 psi max spec and carry part numbers such as TR412, 413, 414, 418, 423 and the large dia. TR415 & 425.  The difference is the total length which runs from 0.88 to 2.00 outside the rim surface.
Note. some have chrome covers but are still basically the same rubber valve under the thin cover. Do not be mislead into thinking these chrome valves are like the bolt in metal valves. Look for the TR number.

 The picture to the right comes from AllTireSupply
and you can order valves from them.
 I would never use any of these rubber valves if
 I have a TPMS or on any RV.

The next group of valves are bolt-in metal and are rated for 200 psi. Now these are designed to fit the same wheel hold dimensions as the above passenger & light truck wheels. Some of these will come with two different size grommets so you can fit either diameter hole. Just be sure you get the correct grommet.

These carry the P/N TR416 or TR416s for the small dia hole depending on which size wheel hole and these are about 1.4" long. This picture comes from MeyersTireSupply. They are a wholesale company in Akron, OH so you may need to get the name of a dealer in your area from the Meyers web site. They also have a 2" long TR416L. The nut torque on this type valve is 25 - 45 in-lb

There are also special High Pressure snap in valves rated for 80 or 100 psi cold set pressure as this one also from Alltire Supply

The 80 psi valves carry the P/N 600HP & 601HP at 1.2" & 2" long

 The 100 psi 801HP & 802HP are 1.3 and 2: long

You will probably find these on new larger pickups .

 Now we move to the big boys for larger "Truck/Bus" applications which for the RV owner means 17.5, 19.5 and 22.5 diameter wheels. There are some that are made especially for aluminum truck wheels but the standard bolt in valves are rated for 200 psi. These fit a hole dia of 0.618 to 0.633". These come in a number of lengths both straight and bent to 90°. Their P/N are TR500, 501, 570, 571, 572, 573, 574, 575. If bent there is a "c" suffix. The nut on these should be tight to 35-55 in-lbs

Your application will probably depend more on your wheels that the selection for small trailers and other vehicles with 16" or smaller dia wheels. When you discuss buying valves you should have your wheel information available.

Now remember if you have aluminum wheels you may need special valves. The valves should use tire mounting lube on the grommets when installing. You should replace the rubber valves or rubber grommets whenever you change tires. I would squirt each valve with Windex or some spray cleaner and confirm it does not wiggle in the hole at least once or twice a year to ensure the nut is not loose and the grommet is still sealing properly.

Bottom Line
Valves are only a couple bucks each so it is false economy to not replace them every time a tire is dismounted. Always use metal caps or TPMS sensors on the end of your valve stems to keep dirt of the core. If you have a lot of dirt or mud on the valve wash it off before removing the cap or TPMS..

Wednesday, January 16, 2013

Can I mix Load Range ?

There was a question about mixing tires of the same size & design on an axle if the Load Range is different.

First we need to all understand what is meant by "Load Range". The official definition as published in the Tire & Rim Association yearbook says "Load Range with a letter (A, B, C, etc), Standard Load, Light Load and Extra Load are used to identify a given size tire with its load and inflation limits when used in a specific type of service, as defined in the heading of TRA tables".

Basically "Load Range"identifies the max inflation for that specific size and type tire and the load capacity of the tire when set to that pressure. many think of it as Ply Rating 2, 4, 6, etc. I previously covered Load Range and Ply Rating in THIS post.

But what do you do if you have to replace one tire on an axle because of some failure like a puncture, impact or even a "Blowout" and can find a matching tire of the same size and type but of a different Load Range?

If you are replacing the failed or damaged tire with a higher Load Range you can run it as if it was of the lower Load Range.

Example 1. You have an ST225/75R15 LR-C and can only get a LR-D.  Your Placard indicates you should run 50 psi cold. Since you know you should always run all tires on any given axle at the same pressure your only option is to inflate the LR-D replacement to 50 psi. Later on you may want to increase your RV load capacity so you may want to get another LR-D and then inflate both tires to 65 psi which will increase your load capacity of the tires by over 300#
 BUT you need to confirm the wheel is rated for 2540# and 65 psi. You will need to contact the wheel manufacturer to confirm the wheel is so rated. I am not sure if i would accept what either the RV dealer or even the RV manufacturer says as they might not have all the engineering data or have other reasons to state a lower capacity.
You will also need to confirm you are not overloading the axle or springs or frame by increasing the load.

There is another reason to increase the inflation but not increase the actual load beyond the original max of 2150#. By running the tire at the higher inflation you are giving yourself a larger "Reserve Load". Some consider this like a safety margin. By running the higher inflation at the lower load you will also decrease the internal structural loads the tire has to tolerate and this should give better durability.

Example 2. Your RV placard indicates you should br running 255/70R22.5 LR-H but you can only find LR-G. In this case you are really out of luck unless you know for certain that you have less than 5205# load and not something any higher. The LR-H tire is rated to carry 5510# at 120 psi while the LR-G is only rated for 5205# at 110psi. This may not sound like much but you should not run your tires in overload as you will do structural damage to the tire which could lead to a reduction in life and even a tire failure under some conditions.

If you are running the highest Load Range for your size you may want to consider carrying a spare tire and let the road service mount your old used spare to be used to get you off the highway. This way you will not be spending hundreds of dollars for a tire you can only use for a few miles.

Tuesday, January 8, 2013

Reporting tire failure to NHTSA Part 2

Now we get to the details. Following are instructions and screen shots of what you will see once you visit the NHTSA web site.

Before you start:
You need to collect all the information you will need to complete the complaint form. This information includes Tire Make or Brand, Tire Line, Size, Complete DOT serial. Also the RV Make, Model, year, VIN and mileage.

I suggest you review these steps first.


OK we have covered a lot of ground and are not done yet but I feel this is enough for now as I don't want to put anyone to sleep.

I think you can see why it is a good plan to assemble all the information details you will need before you start the complaint form process.

It really isn't important that you remember all these steps. I do suggest you bookmark this series of posts so that if you ever do need to file a complaint you can come back to these instructions.

One more post and we will be done with this topic of how to file a complaint.