Trailer tires vs. truck tires.

[BigH]

Originally Posted by Susquatch

Didn't say it WOULD BE, said it COULD BE.

As far as arguments go, consider the following: Higher ratings usually (but not always) go hand in hand with higher design pressure. Higher pressure impose higher tire forces on the chassis and suspension. Higher ratings without the designed higher pressure can mean excessive sidewall flex and poor tire patch contact and control. The manufacturer specifies a tire in cooperation with tire manufacturers that takes load range (min to max), suspension design, and control into account. The only justification for increasing the load rating is to account for higher than design loads (which is a bad idea to begin with).

Now, consider again my choice of words. COULD BE is not the same as "would be". Tire load ranges usually overlap. Therefore, it is sometimes desirable to increase the tire load rating if the trailer is always loaded near its maximum rating. But again, the manufacturer chooses load ratings and tire pressures that satisfy all loads within the design ratings so this isn't really necessary.

For those who do like to use a higher tire rating than specified by the manufacturer, here is something to think about.... What pressure should you inflate the tire to? The one on the sidewall of the tire, or the one on the trailer tire placard, or your own recipe? Also, didn't you ever wonder why there is a tire placard on the trailer? Tire placards are there because the motor vehicle safety standards require it. They require it because tire design and pressure ratings are all safety related parameters. They shouldn't usually be messed with unless you are an engineer with a thorough understanding of how all these factors affect the safe operation of the trailer.

Anyway, my advice is to trust the manufacturer. They put a lot more into the choice of tire than we might all think. If you really want to upgrade your tires, buy a premium tire with the same load parameters.

Higher pressures will in no way cause more sidewall flex.

The manufacturer orders a trailer for a specified weight...the trailer supplier provides a trailer frame with the cheapest tires that meet the spec.

It COULD BE that you can trust the engineers for a better spec tire...
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

[BigRockr]

As usual with this topic, we are blessed with opinions and zero facts . The biggest problem with that is the newbies read this and take it as fact and it is not. No one in this thread knows how the tires on an RV get there with regards to the engineering aspect.

[Airdale]

Originally Posted by 05CrewDually

I'd like to comment on your first paragraph. You are giving the end manufacturer way too much credit. Companies like Forest River approach a chassis builder like Lippert and tell them the specs with an estimated weight figures & dimensions. Then Lippert orders axles in bulk for the chassis they're going to build. Most cases another company supplies wheel/tire combos for a specific weight axle. Unless Forest River specs it out in a specific request for a certain tire, then it is upto Lippert or the axle supplier to throw on whatever tire/wheel comes in. Some higher end manufacturers have spec'd out LT tires for good reason.
By the time the trailer is built for a customer it can weigh more than what the tires and axles supplied are even rated for at capacity. This has happened. I would not put the manufacturers on a pedestal because they're main thing in mind is cost. If they can save 20 bucks a tire by putting on a marginal barely capable tire or axle or chassis for that matter, they will & have done so.
My next response to your second paragraph, you said yourself you are aware of all the testing that goes into a motorized vehicle tire for dependability, quality, safety, ect.... trailer tires, not so much. Is there any? The way they don't last and grenade how could they have been? There's a reason it says right on ST tires "For Trailer Use Only" and I strongly believe it is because the manufacturers know the ST tires are bombs and they don't want lawsuits from an ST tire failing causing a motorized passenger vehicle to crash. If a trailer tire blows out, no big deal. But if a truck tire manufacturer consistently has blow outs it's going to be a big deal. (Ford/Firestone)
ST tires Special Trailer Service (ST) are not even required to be UTQG rated. (Uniform Tire Quality Grade) Maybe they should be.
Please if anyone has links for videos or supporting documentation for tire testing performed on ST trailer use tires I'd like to see them.

I'd like to comment on your first paragraph. You are giving the end manufacturer way too much credit. The “end manufacturer” has overall responsibility to insure and certify the vehicle safety. Companies like Forest River approach a chassis builder like Lippert and tell them the specs with an estimated weight figures & dimensions. Then Lippert orders axles in bulk for the chassis they're going to build. Sounds good to me. NHTSA has authorized the vehicle manufacturer to set axle ratings to the vehicle GAWRs, which they also set. Most cases another company supplies wheel/tire combos for a specific weight axle. Unless Forest River specs it out in a specific request for a certain tire, then it is up to Lippert or the axle supplier to throw on whatever tire/wheel comes in. There is nothing wrong with that. Tire brands are not a concern, just their certifications count. Some higher end manufacturers have spec'd out LT tires for good reason. The trailer manufacturer has sole responsibility for the selection of OE tires. Their guidance from NHTSA is the fitments must be appropriate for THAT vehicle.

By the time the trailer is built for a customer it can weigh more than what the tires and axles supplied are even rated for at capacity. There is a basic rule about end weight; “The total GAWR weights shown on the vehicle certification label, when added to the trailer manufacturers recommended tongue/hitch weight MUST not be less than GVWR. This has happened. When it happens it’s usually an easy math and paper fix. I would not put the manufacturers on a pedestal because they're main thing in mind is cost. If they can save 20 bucks a tire by putting on a marginal barely capable tire or axle or chassis for that matter, they will & have done so. You already said they were supplied from an OEM. Again, brands are not normally in the selection equations.

My next response to your second paragraph, you said yourself you are aware of all the testing that goes into a motorized vehicle tire for dependability, quality, safety, etc.... trailer tires, not so much. Is there any? The way they don't last and grenade how could they have been? There's a reason it says right on ST tires "For Trailer Use Only" and I strongly believe it is because the manufacturers know the ST tires are bombs and they don't want lawsuits from an ST tire failing causing a motorized passenger vehicle to crash. If a trailer tire blows out, it’s no big deal. But if a truck tire manufacturer consistently has blow outs it's going to be a big deal. (Ford/Firestone) ST tires Special Trailer Service (ST) are not even required to be UTQG rated. (Uniform Tire Quality Grade) Maybe they should be. To understand tire testing you must first consider the tire’s basic design. The current tire nomenclature is found in its “designated size”. “P” = Passenger. Its testing procedures will revolve around its potential capabilities it’s designed to perform. Same goes for “LT”, “ST” and all other non prefixed metric tires. Do your tires have a DOT symbol on their sidewall? If so their design has been tested. If they are used on the highway and approved for highway speeds, they can carry passengers.


Before you get to deep into UTQG codes you should read their regulations. Here is the link.
https://www.gpo.gov/fdsys/pkg/CFR-20...sec575-104.xml


Please if anyone has links for videos or supporting documentation for tire testing performed on ST trailer use tires I'd like to see them. Standards 571.109 & 571.119 in the FMVSS.

[Airdale]

Originally Posted by BigRockr

As usual with this topic, we are blessed with opinions and zero facts . The biggest problem with that is the newbies read this and take it as fact and it is not. No one in this thread knows how the tires on an RV get there with regards to the engineering aspect.

Basically they are all made the same way. Here is an easy to read flow-chart.

https://www.maxxis.com/technology/how-a-tire-is-made

[18CrewDually]

Originally Posted by Airdale

I'd like to comment on your first paragraph. You are giving the end manufacturer way too much credit. The “end manufacturer” has overall responsibility to insure and certify the vehicle safety. Companies like Forest River approach a chassis builder like Lippert and tell them the specs with an estimated weight figures & dimensions. Then Lippert orders axles in bulk for the chassis they're going to build. Sounds good to me. NHTSA has authorized the vehicle manufacturer to set axle ratings to the vehicle GAWRs, which they also set. Most cases another company supplies wheel/tire combos for a specific weight axle. Unless Forest River specs it out in a specific request for a certain tire, then it is up to Lippert or the axle supplier to throw on whatever tire/wheel comes in. There is nothing wrong with that. Tire brands are not a concern, just their certifications count. Some higher end manufacturers have spec'd out LT tires for good reason. The trailer manufacturer has sole responsibility for the selection of OE tires. Their guidance from NHTSA is the fitments must be appropriate for THAT vehicle.

By the time the trailer is built for a customer it can weigh more than what the tires and axles supplied are even rated for at capacity. There is a basic rule about end weight; “The total GAWR weights shown on the vehicle certification label, when added to the trailer manufacturers recommended tongue/hitch weight MUST not be less than GVWR. This has happened. When it happens it’s usually an easy math and paper fix. I would not put the manufacturers on a pedestal because they're main thing in mind is cost. If they can save 20 bucks a tire by putting on a marginal barely capable tire or axle or chassis for that matter, they will & have done so. You already said they were supplied from an OEM. Again, brands are not normally in the selection equations.

My next response to your second paragraph, you said yourself you are aware of all the testing that goes into a motorized vehicle tire for dependability, quality, safety, etc.... trailer tires, not so much. Is there any? The way they don't last and grenade how could they have been? There's a reason it says right on ST tires "For Trailer Use Only" and I strongly believe it is because the manufacturers know the ST tires are bombs and they don't want lawsuits from an ST tire failing causing a motorized passenger vehicle to crash. If a trailer tire blows out, it’s no big deal. But if a truck tire manufacturer consistently has blow outs it's going to be a big deal. (Ford/Firestone) ST tires Special Trailer Service (ST) are not even required to be UTQG rated. (Uniform Tire Quality Grade) Maybe they should be. To understand tire testing you must first consider the tire’s basic design. The current tire nomenclature is found in its “designated size”. “P” = Passenger. Its testing procedures will revolve around its potential capabilities it’s designed to perform. Same goes for “LT”, “ST” and all other non prefixed metric tires. Do your tires have a DOT symbol on their sidewall? If so their design has been tested. If they are used on the highway and approved for highway speeds, they can carry passengers.


Before you get to deep into UTQG codes you should read their regulations. Here is the link.
https://www.gpo.gov/fdsys/pkg/CFR-20...sec575-104.xml


Please if anyone has links for videos or supporting documentation for tire testing performed on ST trailer use tires I'd like to see them. Standards 571.109 & 571.119 in the FMVSS.

Yes, look at the 109 standards and see how many DO NOT APPLY to ST trailer tires. ST tires are considered as a "Nonconforming tire" and is why it is stated on the side wall for "trailer use only" and is not designed for passenger use. By that being on the sidewall manufacturers DO NOT have to meet those standards written for passenger vehicle tires.

From Standard No. 109
S6.*Nonconforming tires.*No tire that is designed for use on passenger cars and manufactured on or after October 1, 1972, but does not conform to all the requirements of this standard, shall be sold, offered for sale, introduced or delivered for introduction into interstate commerce, or imported into the United States, for any purpose.[Please see PDF for image: ER27MY98.013]


No matter how you slice it, the quality standards are no where near equal between a passenger vehicle tire (LT) and a trailer tire (ST) simply because they don't have to be due to regulations and lack of ST standards.

[Susquatch]

Originally Posted by BigH

Higher pressures will in no way cause more sidewall flex.

The manufacturer orders a trailer for a specified weight...the trailer supplier provides a trailer frame with the cheapest tires that meet the spec.

It COULD BE that you can trust the engineers for a better spec tire...
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Read it again. I didn't say higher pressures create more sidewall flex. I said higher pressures cause more stress in the suspension (because of less flex) and lower pressures cause more flex in the tires.

Totally agree that they use the cheapest tires. I bought high quality tires of the same rating the day after I brought my trailer home. Cheap tires suck.

And yes, I do trust the engineers more than I trust anybody else with opinions on this forum. That has been my whole point all along. You might be correct about the process though. What matters most is that whoever designs and builds the chassis is the one who needs to spec the tires and the chassis loading parameters, and then the cabin manufacturer and the user needs to follow those recommendations. However, if I should find out that engineers are not the ones making these decisions, then I would be first in line petitioning NHTSA to introduce new laws. I would never trust the safety of my family or the safety of other travellers on the highway to the self anointed opinions of anyone (on this forum or at the cabin manufacturer) who does not have the educated professional expertise that is required.

[Susquatch]

Originally Posted by BigH

Higher pressures will in no way cause more sidewall flex.

The manufacturer orders a trailer for a specified weight...the trailer supplier provides a trailer frame with the cheapest tires that meet the spec.

It COULD BE that you can trust the engineers for a better spec tire...
https://www.goodyearrvtires.com/pdfs/rv_inflation.pdf

Read it again. I didn't say higher pressures create more sidewall flex. I said higher pressures cause more stress in the suspension (because of less flex) and lower pressures cause more flex in the tires.

Totally agree that they use the cheapest tires. I bought high quality tires of the same rating the day after I brought my trailer home. Cheap tires suck.

And yes, I do trust the engineers more than I trust anybody else with opinions on this forum. That has been my whole point all along. You might be correct about the process though. What matters most is that whoever designs and builds the chassis is the one who needs to spec the tires and the chassis loading parameters, and then the cabin manufacturer and the user needs to follow those recommendations. However, if I should find out that engineers are not the ones making these decisions, then I would be first in line petitioning NHTSA to introduce new laws. I would never trust the safety of my family or the safety of other travellers on the highway to the self anointed opinions of anyone (on this forum or at the cabin manufacturer) who does not have the educated professional expertise that is required.

Great chart from the engineers at Goodyear. It allows me to optimize the pressure for my load instead of accepting a compromised range. I wonder if charts like this are available for every tire at all the high quality manufacturers. THANK YOU!

[Dave Lyon]

If LT truck tires were better and more cost effective trailers would come with them from the factory...…….but they don't.

[18CrewDually]

Originally Posted by Dave Lyon

If LT truck tires were better and more cost effective trailers would come with them from the factory...…….but they don't.

Yes, some higher end trailers do and have in the past. That has already been proven. LT tires were even listed in brochures.

[BigH]

Originally Posted by Susquatch

Read it again. I didn't say higher pressures create more sidewall flex. I said higher pressures cause more stress in the suspension (because of less flex) and lower pressures cause more flex in the tires.

Totally agree that they use the cheapest tires. I bought high quality tires of the same rating the day after I brought my trailer home. Cheap tires suck.

And yes, I do trust the engineers more than I trust anybody else with opinions on this forum. That has been my whole point all along. You might be correct about the process though. What matters most is that whoever designs and builds the chassis is the one who needs to spec the tires and the chassis loading parameters, and then the cabin manufacturer and the user needs to follow those recommendations. However, if I should find out that engineers are not the ones making these decisions, then I would be first in line petitioning NHTSA to introduce new laws. I would never trust the safety of my family or the safety of other travellers on the highway to the self anointed opinions of anyone (on this forum or at the cabin manufacturer) who does not have the educated professional expertise that is required.

Great chart from the engineers at Goodyear. It allows me to optimize the pressure for my load instead of accepting a compromised range. I wonder if charts like this are available for every tire at all the high quality manufacturers. THANK YOU!

I read it again and I quote: " Higher ratings without the designed higher pressure can mean excessive sidewall flex and poor tire patch contact and control.'' -I still read it the same way but if it is not what you meant I'm ok with it...

Do what you think is best sir... I've researched this and your belief of 'could be' is not going to give me pause that replacing an st tire with a higher rated st tire is a bad idea.

[Susquatch]

Originally Posted by BigH

I read it again and I quote: " Higher ratings without the designed higher pressure can mean excessive sidewall flex and poor tire patch contact and control.'' -I still read it the same way but if it is not what you meant I'm ok with it...

Do what you think is best sir... I've researched this and your belief of 'could be' is not going to give me pause that replacing an st tire with a higher rated st tire is a bad idea.

My meaning is still clear to me but maybe this expansion in all caps and brackets will help.

Higher ratings WITHOUT the designed higher pressure (higher rated tires are typically designed to operate at higher pressure so operating them at lower pressure than their design pressure for that load) can mean excessive sidewall flex and poor tire patch contact and control.

My earlier comments do say that a higher rated tire of the same design could be a benefit if the trailer is consistently loaded at the top end of its load rating. Quite frankly, I would not be afraid of doing that under those higher loading conditions ESPECIALLY if I have the tire manufacturers pressure to load rating chart to make sure the pressure was adjusted appropriately.

It might help you (and anyone else reading this) understand the point I was trying to make if you can appreciate that my main concern about increasing the rating is really all about putting higher rated tires on WITHOUT adjusting the pressure appropriately for those tires. You do appear to understand that even if you don't understand me. So have at it! I'm sure that you will be ok. I doubt the same applies to everyone who might be reading this thread.

For those who don't understand the relationship between load rating, actual load, and tire pressure, I still believe it is best to buy quality tires that comply with the OEM recommendations for both load rating and pressure on the tire placard affixed to the trailer.

I am totally opposed to the idea of using truck tires instead of trailer tires without the benefit of a qualified expert engineer's advice.

[Airdale]

Originally Posted by 05CrewDually

Yes, look at the 109 standards and see how many DO NOT APPLY to ST trailer tires. ST tires are considered as a "Nonconforming tire" and is why it is stated on the side wall for "trailer use only" and is not designed for passenger use. By that being on the sidewall manufacturers DO NOT have to meet those standards written for passenger vehicle tires.

States That Permit Riding in Travel Trailers State laws often set age limitations, typically requiring riders in travel trailers to be at least 14 years of age. In addition, most states require that the fifth wheel trailer has a door that can be opened from both the inside and outside for safety reasons. Some states mandate that passengers in travel trailers wear seat belts. In others, it is required that that windows in fifth wheels be made of safety glass in the event of an accident.

Arizona, Indiana, Iowa, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New York, North Dakota, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, West Virginia and Wisconsin permit passengers to travel in fifth wheels. Of these, Oregon, Pennsylvania, South Carolina, South Dakota and Wisconsin require a source of communication between the driver of the towing vehicle and passengers in the travel trailer for safety reasons.
If you will be traveling in a fifth wheel, consult department of motor vehicle regulations for your state before setting out on your trip and review the rules of other states that you may travel through on your journey.

Fifth Wheel Safety Tips:
If you will be riding in a fifth wheel trailer, take certain steps to ensure your safety. The operator of the towing vehicle should be well rested and drive within the speed limit according to road and weather conditions. A windy day can prove dangerous for riders in travel trailers. Stick to travel on days with winds under 30 miles per hour. Avoid jerky movements and sharp turns, which could cause the fifth wheel trailer to flip. In addition, be sure that your mirrors are large and offer a full view along the entire side of the trailer.

With a bit of preparation, travel in a fifth wheel can be safe and enjoyable. Taking appropriate precautions helps you to remain within the boundaries of the law, as well.

[Johnfort]

Common sense dictates that you should not put anyone you love in a TT or 5th wheel going down the road. Mother-in-laws are okay though.

[JohnD10]

Originally Posted by Johnfort

Common sense dictates that you should not put anyone you love in a TT or 5th wheel going down the road. Mother-in-laws are okay though.

[18CrewDually]

Originally Posted by Airdale

States That Permit Riding in Travel Trailers State laws often set age limitations, typically requiring riders in travel trailers to be at least 14 years of age. In addition, most states require that the fifth wheel trailer has a door that can be opened from both the inside and outside for safety reasons. Some states mandate that passengers in travel trailers wear seat belts. In others, it is required that that windows in fifth wheels be made of safety glass in the event of an accident.

Arizona, Indiana, Iowa, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New York, North Dakota, Oregon, Pennsylvania, South Carolina, South Dakota, Tennessee, West Virginia and Wisconsin permit passengers to travel in fifth wheels. Of these, Oregon, Pennsylvania, South Carolina, South Dakota and Wisconsin require a source of communication between the driver of the towing vehicle and passengers in the travel trailer for safety reasons.
If you will be traveling in a fifth wheel, consult department of motor vehicle regulations for your state before setting out on your trip and review the rules of other states that you may travel through on your journey.

Fifth Wheel Safety Tips:
If you will be riding in a fifth wheel trailer, take certain steps to ensure your safety. The operator of the towing vehicle should be well rested and drive within the speed limit according to road and weather conditions. A windy day can prove dangerous for riders in travel trailers. Stick to travel on days with winds under 30 miles per hour. Avoid jerky movements and sharp turns, which could cause the fifth wheel trailer to flip. In addition, be sure that your mirrors are large and offer a full view along the entire side of the trailer.

With a bit of preparation, travel in a fifth wheel can be safe and enjoyable. Taking appropriate precautions helps you to remain within the boundaries of the law, as well.

Read S6 in my post above. Because ST tires are a NON-CONFORMING TIRE, they can not be used or sold for passenger service in the US. Again, Trailer Use Only. That's why it is written on the sidewall. Letting people ride in a trailer with ST non-conforming tires is not legal. LT tires installed would make it legal per some state laws.

[Airdale]

Originally Posted by 05CrewDually

Read S6 in my post above. Because ST tires are a NON-CONFORMING TIRE, they can not be used or sold for passenger service in the US. Again, Trailer Use Only. That's why it is written on the sidewall. Letting people ride in a trailer with ST non-conforming tires is not legal. LT tires installed would make it legal per some state laws.

Description of non-conforming tires.

https://www.pacode.com/secure/data/0...59/s159.6.html

Just a Note: All of our tires with the DOT symbol on their sidewalls are, at some point, tested. There isn't much use in testing a tire for dive and steer axles when it's design does not include features for those functions.

In another thought. Directional tires. Like other specialty tires, have markings on their sidewall to show the direction for forward rotation. Probably been tested for that direction. Probably have specific instructions for rotation to ensure they are still rotating properly after the rotation. They are designed for a specific function and probably work best when operating within the parameters set for that function. Guess who makes the decision for their use as original equipment tires? The Vehicle Manufacturer.

[18CrewDually]

That is alot of "probablies".
But I believe I said all that I need to, so other folks can take what they want from it.
For my 5 trailers, its LT's. That is 22 tires in total, ranging from 2k to 23k pounds loaded and never a blow out in all the years. I did find a screw in one once.
Drive Safe.

[shopboss]

I run Firestone TransForce on my one ton dually, so I really thought about using them on the camper trailer. Then Good Year released the Endurance series ST tires. I ordered 5 of them online from Simpletire.com. We replaced the China bombs that had 4K miles on them. I was nicely surprised it only took a quarter Oz. of weight per tire to balance them. We went from 8 ply to 10 ply. I feel the ride is better, stability is better, and I paid an American worker to build them.

[Regg]

Originally Posted by KellyG

When we bought or Shasta Oasis with its China bomb tires, we knew nothing about speed or load ratings, and so drove continuously at freeway speeds (here in the west, 75-85 actual). After a few thousand miles with no problems, we found out about the limits (!) and slowed to 65-70 (or so) with them.

I can't believe that you would fly down the road at 75-85 mph!
And then believe 65-70 mph is a fine thing to do!
You have been very blessed to not have wrecked your own rig or have involved innocent others around you!
You are an accident waiting for a place to happen!
Take your 8,000 - 9,000 lb vehicle and 9,000 - 10,000 lb outfit and park it!

[BigH]

Originally Posted by Regg

I can't believe that you would fly down the road at 75-85 mph!
And then believe 65-70 mph is a fine thing to do!
You have been very blessed to not have wrecked your own rig or have involved innocent others around you!
You are an accident waiting for a place to happen!
Take your 8,000 - 9,000 lb vehicle and 9,000 - 10,000 lb outfit and park it!

What's the matter Regg? If your rig handles so poorly that you can't drive relaxed at 65-70mph (or more) when the conditions allow then you should stay home until you get a setup that tows correctly...