TireHobby

Trailer wheels are lug centric and cannot be properly balanced without a lug centric balancing adapter.

Nitrogen Information.

 

https://www.ustires.org/sites/default/files/TISB_44_USTMA.pdf 

You have a very popular tire size. All of the ST tire manufacturers here and over there build that tire in four different load ranges, LRC, LRD, LRE & LRF. At the very minimum, pick the load range that matches your OE tires. Narrowing it down to a brand will depend on your personal research of each considered.

 

Note: All of the LRF tires will be steel cased. 

On 9/27/2019 at 4:40 PM, SWharton said:

 

Just wanted to check with those in the know if thee was something inherently wrong with doing this.

Without some sort of approval from the vehicle manufacture, it's a safety violation. 

The can of worms is opened when worrying about exact tire temps. Here is one of them.

Running tires are in thermal equilibrium between the generation of internal heat due to the viscoelasticity of the rubber material and the effects of their thermal environment. Since the viscoelasticity shows temperature dependency, there is a strong correlation between this thermal equilibrium and the rolling resistance. However, there are only few methods which can be used for estimating the amount of rolling resistance of an actual running vehicle using this correlation. In this paper, we would like to estimate the temperature distribution in the running tire by means of the quasi-static model of the finite element method (FEM) in consideration of the thermal environment of real road driving and introduce an approach toward estimating the rolling resistance of an actual running vehicle based on the correlation between the temperature distribution in the tire and the rolling resistance.

 

The best info is from the tire manufacturers data books. Lots of them are on line. 

11 hours ago, Rich&Sylvia said:

Run the tire pressure at the maximum for which the tire is rated on the truck.
The trailer, I don't know.

I run my TC (truck camper) at 80 psi and have for years.  Current TC weight is 14,000 pounds and towing a 5,500 tow vehicle.
What you may notice at high vs low tire pressures is vehicle handling.  

Remember that, tire pressure recommendations are good even for tires that are near completely worn out.  
There is a wide safety margin built in.

The very common Dana 80 axle, as used on many 350/3500 products, direct from the axle manufacturer (not Ford, Dodge, GM, etc) is for 11,500 pounds.
Vehicle manufacturers de-rate the axle rating (GAWR) to conform more to the tire maximum load capacity.
Thus, you will find that an vehicle's tag will rate the axle load to within a few hundred pounds of the tire load capacities. 

I've made the Dana Axle Spec Sheet available here: https://www.eaglecapowners.com/owners/showthread.php?tid=224

 

Vehicle manufacturers sets axle GAWR to comply with vehicle specifications needed to comply with vehicle certifications. Whatever axle manufacturer's specifications exceed the vehicle GAWRs is considered reserve load capacity. Tire load capacity is based on maximum GAWR and the regulations that stipulate tire load capacity reserves for automotive vehicles.

NHTSA does not knowingly allow deviations from vehicle certifications. Recalls for inaccurate vehicle labeling can be very expensive for vehicle manufacturers, yet we see them almost weekly because some vehicle manufacturers are lackadaisical about the process.  

1 hour ago, SKP073615 said:

The way I understand this is that the ideal tire contact batch occurs when the tire pressure matches the load on the tire, as per the manufacturer's weight chart.  Tire wear and traction are optimal when at this point.  Under inflation is always worse than over inflation and one should err to the higher pressure side.  RV manufactures may install tires rated above the rating of an axle.  Running at sidewall pressure in these cases is definitely higher than needed, but still better than under inflation.  Running through a CAT scale to get at least axle weights is pretty easy.  If tire position weights are not known, the best temporary practice is to run the tire at the max cold pressure listed on the tire sidewall.  Never inflate tires above their listed sidewall pressure (cold).

Note, that without weighing,  tires/axles can be overloaded without knowing it.

Art

Because you have a bus you may see inflation pressures differently from FMVSS standards. That’s because of so much disinformation about tire inflations for such vehicles. Many feel its ok for them to use FMCSA regulations in place of FMVSS standards because of the use of commercial tires. FMCSA regulations are not applicable to FMVSS standards. The vehicle certification process of the final stage manufacturer is the factor to consider when applying tire inflation pressures. If there is no provision in your vehicle’s owner’s manual or an auxiliary tire information placard for optional inflation pressures and the federal certification label lists recommended cold inflation pressures for the OE tires, that information is correct and the FMVSS outlaying the maintenance for those standards is FMVSS.

 

 

The following information is a verbatim quote from a USTMA  publication about proper inflation of motor home tires fitted using FMVSS.

 

 

“Determining Proper Inflation Pressure Use of the tires, wheels, and inflation pressures as specified on the vehicle tire placard, certification label or in the service manual ensures that these components can carry the maximum rated axle loads (GAWR) and maximum vehicle weight (GVWR), and also maintains other performance characteristics, if any, intended by the vehicle manufacturer.  At a minimum, the tires on each axle should not be over loaded or under inflated if the vehicle is properly loaded.

With actual weights of the loaded RV acquired by weighing, it is possible to compare them against the GAWR, GVWR, and tire capacities posted on the vehicle tire placard or certification label. These actual weights are also what should be used to determine any increase in inflation pressure for the tires, if required.

Inflation pressure recommendations may also be determined based on the tire manufacturer’s specifications, which define the amount of inflation pressure necessary to carry a given load. These inflation pressures may differ from those found on the vehicle tire placard or certification label.

However, never use inflation pressure lower than specified by the vehicle tire placard, certification label or owner’s manual. Nor should inflation pressure exceed the maximum pressure molded on the tire sidewall."

6 hours ago, Ray,IN said:

 

Axle weights; each axle has a maximum weight capacity, tires on this axle also have a total maximum weight capacity, the lesser of those two determine maximum axle weight.

 

The official load for an axel is determined by the vehicle manufacturer and displayed on the vehicle certification label as GAWR. OE tires NEVER provide, a load via recommended cold inflation pressures less than GAWR.  

People often ponder over tire inflation pressures. Everyone seems to have a solution. This is how it’s advertised and supposed to be done. My reference material is from NHTSA, FMVSS & USTMA.

 

This is for all Original Equipment (OE) tires. “The correct inflation pressures” for them under, normal operating conditions is the vehicle manufacturer’s recommended cold inflation pressures found in the vehicle owner’s manual, on the tire placard and certified on the vehicle certification label. Conditional deviations may be provided on a vehicle manufacturer’s label for special conditions such as towing. The vehicle owner’s manual is the place to look for vehicle manufacturer deviations.

 

When OE tires have some reserve load capacities available, optional inflation pressures between what has been recommended and what may be used to provide maximum load capacity from the tire are always optional. Gray area if you prefer.

 

Load inflation charts are standardized per designated tire sizes. They do not provide recommendations. They are a tool used by manufacturers and other experienced installers to determine a correct tire inflation.

 

Automotive tires MUST provide load capacity reserves. Manufacturers usually increase the vehicles GAWR values to provide the tire load capacity reserves. RV trailer tires are required by regulation to provide a load capacity equal to or greater than the vehicle certified GAWRs. It has proven to be flawed but still exists. RIVA has stepped in and require all of their participation members – about 98% of all USA RV trailer builders – to provide OE tires with at least 10% of load capacity reserves above GAWR axle maximum loads.

 

The USTMA mentions in their procedures manuals a procedure to inflate RV tires to a load carried. However, they protect that statement with the caveat; “Never inflate tires below the vehicle manufacturer’s cold recommendations”.

 

Because FMVSS (standards) are minimum, OE tire Designated sizes are considered by USTMA to be the minimum standard and protect that standard with the caveat; “Replacement tires MUST not be smaller than the OE tires and they MUST provide a load capacity equal to the OE tires”. Of course when the designated size is changed, the placards are no longer valid. A new cold recommended inflation pressure must be established that provides a load capacity for the replacement tires equal to or greater than the OE tires provided. NHTSA allows an auxiliary placard for that information. The installer should put the new information on a placard and place it adjacent to the original placard. The installer should inform the vehicle owner of the new recommended cold inflation pressures so the vehicle owner’s manual can be updated.

 

On RV trailers with recommended cold inflation pressures equal to the tire maximum for the load, there are no inflation options other than maximum. Or, install tires with a higher load range, if possible. They will conform to the certification label but have load capacity deserves higher than the lower load ranged tire.

 

Bottom line: Vehicle recommended inflation pressures for OE tires are the correct inflation pressures. If you have a load higher than what the OE tires provide, your axle is overloaded.     

In the world of how it's supposed to be done, upgrading the axles does not require tire upgrading. The GAWR on the federal vehicle certification label is always valid, unless it's officially modified. Only the vehicle manufacturer or a certified vehicle modifier has the authority to change vehicle certifications. 

 

Hypothetical; a RV trailer having a GVWR of 22,000# can be certified for three 6,000# vehicle certified axles, providing the vehicle manufacturer's recommended tongue weight is 4,000#. Those axles are often 7000# axle manufacturer certified, allowing heavier braking capabilities. The trailer manufacturer is authorized to degrade axle manufacturer certifications for the purpose of vehicle certification. That's why, back in the day of the popular LT235/85R16E tires, they got fitted to such a heavy trailer.  

7 hours ago, Consolenut said:

Yes bought it used. I seen the tires and new they needed to be replaced and off to the trailer place i went. Instead of the 235/85/16. I went straight to 17.5..........235/75/17.5 to be exact best thing I ever did.

👍

2 hours ago, Consolenut said:

The GY614 are maxxed and looked flat at the bottom under my teton. They were gone a week after I bought it. I went to 17.5 commercial trailer tire. Rated at 6005 per tire they don't even blink with the Teton on it. My axles are rated at 8K on the sticker on the side of the unit. 24KGVWR.  By going to to 17.5 and there weight rating they seem to have less rolling resistance. They remain round and the 614 seem to be flat along the ground where they were in contact with the road.

Of course I have a super heavy weight in the 5ver world. 

Did you buy the Teton used? Having a maximum load capacity of 3750# @ 110 PSI the G614s have never qualified for fitment to vehicle certified 8000# axles.

On 9/13/2019 at 8:11 PM, FBO Cookie Monster said:

So far, not really interested in a trailer. I like the total length of this thing. 

The GVWR of my truck is 7800 lbs. 

I have a pic of the trailers sticker, I *wish* it went to 9995 lbs. it does not, only 8800 lbs, leaving a ccc 1600 lbs.  Their math is fuzzy. It has 5100 lb axles installed. Maybe the frame can’t take the weight? If I can figure out how to reduce pixles on this ipad I’ll post that pic.

 

Anyways, I plan on the B&W flip ball, or their competitor. That, with an AUH should weigh less than 100lbs. 1400 lbs on the pin leaves 1000 lbs for me, my wife, and my dog. Heck, maybe enough for 2200 watt Honda!

GCWR is over 17,000 lbs, Rear axle 4800. Looks ok on all of those. Fuel is included btw, for payload. Just not total gcw.

Your trailer certification label is a mystery. Maybe they used some logic unknown to other manufacturers. The certified axles for a 8800# GAWR trailer don't need to be certified beyond 4400#. The 5100# are 700# above minimum requirements and invite overloading. I'm betting the axle manufacturer's tag on those axles are 5200# and recertified for the trailer to 5100# because the installed tires would not meet the 10% RVIA recommendation for reserve load capacity on 5200# axles. They could have used those tires in a LRD or LRE with 4400# axles.

 

2 hours ago, Second Chance said:

None - and it would be a good move (going to the Sailuns) in my opinion.

Rob

It depends on where your rig is registered. Some states and provinces have periodic RV trailer inspections. Here in the USA there is a federal regulation outlining the minimum requirements for such inspections so that all DOT (NHTSA)  tire safety standards are met.

Here is a sample of one section of that regulation: https://www.law.cornell.edu/cfr/text/49/570.62

 

3 hours ago, TXiceman said:

G614 Specs

According to the GY spec sheets, the tire is rated at 3750 # in a single wheel location.  Two these on an axle will give you a load rating of 7500# at 110 psig air pressure..  This will easily support a 7000# rated axle.

Ken

A consumer is not in compliance with industry standards when they choose replacement tires with less load capacity than the Original Equipment tires.

The RVIA recommendation is just that, a recommendation. However, about 98% of all RV trailers built in the USA are manufactured by RVIA members and are already complying with the recommended 10% load capacity reserve above vehicle certified GAWRs.

Tire industry standards (USTMA) fully support the vehicle manufacturer's Original Equipment tire selections as a minimum requirement. They publish their support with a statement similar to this one; 

Never choose a tire that is smaller in size or has less load-carrying capacity than the tire that came with the vehicle.

Tires should always be replaced with the same size designation — or approved options — as recommended by the vehicle manufacturer.

The correct tire size designated for your vehicle should always be verified with the information in your vehicle owner’s /vehicle certification label.

That's a quote from the Michelin tire replacement SOP. Similar statements will be found at all retail outlets.

 

2 hours ago, Randyretired said:

When you say can't use the heavier tire, what does that mean.  Am I going to go to jail or invalidate my insurance?  My Teton has 7000 pound axles but came with LT tires.  I have been considering Sailun tires.  What authority says I can not do that?

Can't was a strong word. Not supposed to is a better fit. I know the heavy trailers like yours come with 7000# axles, but, what are they certified to carry. Their official load capacity, once they are fitted to the trailer will be listed on the vehicle certification label. Teton may have used heavier axles to provide better braking and just derated their load capacity to conform to vehicle certification regulations. The only LT tire with enough load capacity to satisfy the needs of 7000# axles was the GY G614. My regulations binding on the vehicle manufacturer the tires fitted to RV trailer axles MUST provide a load capacity equal to the axles maximum vehicle certified GAWRs.

I've been writing about tires for a long time and I try real hard to stick to industry facts rather than what "he said, she said talk".

Tire industry standards revolve around safety. If you add to them all is well. 

On 8/28/2019 at 12:24 PM, stolpsaddles said:

Time to purchase new trailer tires for my horse trailer.

I currently have Goodyear g614 14ply and have been good but my local Kal tire does not deal with Goodyear. Looking for opinions on the Carlise Radial Trail HD.  My concern is the Goodyear is 110 psi and the Carlise is 95psi. Also the Goodyear are more than twice the price.  Had Crossfire on before and did not like the damage the blowout did after 2 years of use.

You should research these. 

https://www.carlislebrandtires.com/our-products/product-detail/csl-16

On 8/28/2019 at 12:24 PM, stolpsaddles said:

 

 

 

I’ve read all the posts in this thread and because of them I've decided to start from scratch with this post.

Are your trailer axles described on the vehicle certification label 7000#? If so, the GY G614 tires are no longer considered to have enough load capacity for 7000# axles. Of course that info is not binding on you, it’s just info that nearly all RV trailer manufacturers must follow when installing Original Equipment tires (OE) on new trailers. About 98% of all USA trailer manufacturers are members of the RVIA origination. RVIA has mandated a recommendation that all members provide OE tire having a 10% load capacity reserve above the trailer’s certified GAWRs. For the 7000# axles that’s a minimum requirement of 3850# per tire which the G614 cannot provide.

Tires are fitted to RV trailers by designated size and the load range lettering system for ST/LT tires. Passenger tires use the load index number system.

Steel cased trailer tires are being manufactured by most of the major “off shore” trailer tire builders and some are more popular than others. GY was first with their G614 RST and quickly mimicked by Sailun. A few years ago Sailun started building a couple of LRG ST tires. They are ST235/80R16 rated at 4080# @ 110 PSI and ST235/85R16 rated at 4400# @ 110 PSI. Other than load capacity the tire height between the two can become critical for RV trailer fitments because of axle placements. Many trailers heavy enough to need those tires have 32” axle spacing and the 85 tire is too tall. 

Tire industry standards require replacement tires to have a load capacity equal to or greater than what the OE tires provide.

Your trailer’s owner’s manual is going to tell you to use replacements of the same designated size as the OE tires or others recommended by the vehicle manufacturer. Therefore, you can’t use a LT235/85R16 LRE to replace a ST235/85R16 because, 1  the designated sizes differ (ST-LT) and 2, because the ST provides 3640# of load capacity as opposed to the 3042# of load capacity provided by the LT.

Other well known brands building steel cased ST tires are Carlisle, Heartland & Greenball, just to name a few found at numerous retail outlets and big box stores. Greenball has already sent a new steel cased ST225/75R15 LRF to retailers. Load capacity, 3195 @ 95 PSI.

 

Oh, by the way. The GY Endurance ST trailer tire has a new designated size and is currently unique to that brand. it's the ST255/85R16 LRE with a load capacity of 4080# @ 80 PSI. But, it's tall, over 33". It's a polyester tire with 3 belts, nylon overlays and sidewall scuff guard which makes it heavier.   

 

Been watching this thread for awhile. Very hard to give answers without knowing the trailer’s actual tires specs. But I can answer some of the questions with hypothetical analogies.

I looked at the current specs for 19” KZ TTs.  Some are 3500# GVWR and others are 4000# GVWR. Some have 14” tires and others have 15” tires. 

Tire fitments are not at the whim of the trailer builder. They must be appropriate for each GAWR. The specific information can be found on the trailer’s federal certification label. Tire placard and in the vehicle owner’s manual. The certification label has a standard physical location on trailers. It’s onj the LH forward external section of the trailer. Normally the tire placard will also be displayed in the same location. 

The tire size (s)  listed on the certification label must be the same size as those installed on the trailer at the time of first sale. Those Original Equipment (OE) tires set the standard for all subsequent replacements. Industry standards require replacement tires to have a load capacity equal to or greater than the OE tires.

It is often very difficult the use replacement tires for ST tires in the 14” - 15” diameter range with tires from another design (P/LT). Even if some are found that will work the tire industry frowns on such applications and may void all warranty coverage for such fitments. Most trailer owner’s manuals will have a canned statement such as this;  “To maintain tire safety, purchase new tires that are the same size as the vehicle’s original tires or another size
recommended by the manufacturer.”

Another problem with 14” & 15” tires is the wheel/rim load and psi limits. Trailers with that sized tires are often built very close to the specs to keep costs low. Therefore, a LRD tire of the same size as an OE LRC tire might exceed the OE wheel/rim assembly’s  load and/or PSI limits.

ST tires work well when properly maintained and operated within their design specifications. However, like other highway tires they need load capacity reserves to offset degrading. Unlike other DOT highway tires, load capacity reserves are not factored into the fitment equation for RV trailer tires. 

Brands? What works for the goose may not work for the gander. 

If an owner does not, at least once in awhile, find out what each tire is carrying, load wise, brands wont make a difference. One might last a little longer than another but in the end the overloaded tire is going to fail.

Best fitments? Go up a load range and air all tires to the recommended sidewall pressures.