Trailer King II blow out with RV damage
- Thread starter Jeff F250
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FastEagle
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I?m not writing this to support any manufacturer. It?s just facts that RV trailer owners should be more aware of.
Original equipment (OE) tires for RV trailers are installed by the trailer manufacturer in accordance with Federal Motor Vehicle Safety Standard (FMVSS). Those standards are written to insure minimum safety standards are complied with.
The standards for RV tire fitments read, in part, like this. OE tire fitments must have a load capacity, via the recommended cold inflation pressures deemed appropriate for that trailers GAWR weights. Another section of the same standard reads like this; The trailer?s total vehicle manufacturer?s certified GAWR weight, added to the trailer manufacturer?s recommended/published tongue/hitch weight, must not be less than GVWR. NOTE: The axle manufacturer?s tag on the individual axle may not be the official GAWR for that trailer. The trailer manufacturer has the option to set GAWRs appropriate for the trailer. So, look on the vehicle certification label for the official values.
It is not uncommon to find trailers with tires that just barely meet the minimum specs. RVIA has a new recommendation to it?s participating members to install OE tires with a minimum of 10% in reserve load capacities. However, that is not a binding recommendation for the trailer manufacturer (YET).
Making a complaint to NHTSA isn?t going to carry much weight without proper documentation. They, just like all other?s, know RV trailers are seldom under their cargo capacity. Some maybe just a single wheel position, others an entire axle and yet others just completely overweight. A tire forensic expert will know, just as soon as they inspect what?s left of a catastrophic tire failure what the probable cause was.
Chapter #4 of the reference provided below has all the information you need to know about getting your RV weights from a stop at some scales.
https://www.ustires.org/sites/default/files/CareAndService_PassengerAndLightTruckTires.pdf
Original equipment (OE) tires for RV trailers are installed by the trailer manufacturer in accordance with Federal Motor Vehicle Safety Standard (FMVSS). Those standards are written to insure minimum safety standards are complied with.
The standards for RV tire fitments read, in part, like this. OE tire fitments must have a load capacity, via the recommended cold inflation pressures deemed appropriate for that trailers GAWR weights. Another section of the same standard reads like this; The trailer?s total vehicle manufacturer?s certified GAWR weight, added to the trailer manufacturer?s recommended/published tongue/hitch weight, must not be less than GVWR. NOTE: The axle manufacturer?s tag on the individual axle may not be the official GAWR for that trailer. The trailer manufacturer has the option to set GAWRs appropriate for the trailer. So, look on the vehicle certification label for the official values.
It is not uncommon to find trailers with tires that just barely meet the minimum specs. RVIA has a new recommendation to it?s participating members to install OE tires with a minimum of 10% in reserve load capacities. However, that is not a binding recommendation for the trailer manufacturer (YET).
Making a complaint to NHTSA isn?t going to carry much weight without proper documentation. They, just like all other?s, know RV trailers are seldom under their cargo capacity. Some maybe just a single wheel position, others an entire axle and yet others just completely overweight. A tire forensic expert will know, just as soon as they inspect what?s left of a catastrophic tire failure what the probable cause was.
Chapter #4 of the reference provided below has all the information you need to know about getting your RV weights from a stop at some scales.
https://www.ustires.org/sites/default/files/CareAndService_PassengerAndLightTruckTires.pdf
Gary RV_Wizard
Site Team
Max load ratings are pretty much constrained by the tire size, so there is only so much you can get with a reasonable width, 15" or 16" tire. I've seen a very few trailers with 19.5" wheels, but that is high end custom stuff. A 16k 5W will have a minimum 3200 lb, leaving 12,800 lbs on two trailer axles. Four tires, thus needing 3200 lbs each minimum. 3600-4000 lbs per tire is decent for that amount of weight. The axles are probably rated at 7000 lbs each anyway.
Some large and well-equipped trailers have three axles, simply because of their weight, which may go to the 17k-18k range. Two axles with 19.5" wheels would be a better towing solution in most cases, but tire height is a concern because it raises the center of gravity and the wheel wells intrude more on the interior.
A 15k-16k trailer can have a 20 percent hitch weight = 3000-3200 lbs which may leave around 12800 lb on the trailers axles or 3200 lbs per tire approx weight.Sun2Retire said:
The commercial grade all steel ply carcass Sailun S637 is the probably most popular G load range in the 16" size for the commercial regional service trailer industry and fast becoming the preferred 16" G tire on rv trailers. It comes in a ST235/80-16 G at 4080 lbs capacity.....or a ST235/85-16 G at 4400 lbs capacity. These tires work great on trailers with 7k and 8k axles.
5k and 6k axles the commercial grade all steel ply carcass Bridgestone R250 or R238 comes in the usual 16" LT E sizes and up to 3042 lbs per tire.
Most rv trailers I've seen with 8k and heavier axles are using the 17.5" load H wheels and tires. Sailun S637 come in this size also and have 6008 lb ratings at 125 psi ....which of course can be overkill for a 15-16k gross weight trailer.
Back2PA
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longhaul said:
This answers my question. Assuming there are no clearance issues with the taller tire one could get another 10% margin
Bobtop46
Well-known member
Don't just look at the weight rating of a tire. Look at the speed rating. ALL tires have one. Combine near maximum load with exceeding the speed rating or maxing it for hours on end and tire goes boom. I would be a rich man if I had a dollar for every 5er/TT goes blowing by me (at 65 mph) only to be seen a 10 minutes later down the road with a blow out.
As far as speed rating goes, would you drive your car or truck at max RPM for hours on end? Know the max speed and leave some safety margin.
As far as speed rating goes, would you drive your car or truck at max RPM for hours on end? Know the max speed and leave some safety margin.
Back2PA
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Bobtop46 said:
True, all ST tires have a 65 MPH rating
Bobtop46
Well-known member
Tire Tech: Trailer Tires vs. Passenger Vehicle Tires
There are differences in the driving requirements between the tires on your trailer and those on the car or light truck you use to tow it. Therefore, there are distinct differences between the way trailer tires and tow vehicle tires are engineered.
Your tow vehicle is a leader, which means traction is a key focus in the design of its tires. Traction allows your tow vehicle to accelerate down the road, turn around the corner and brake to a stop. Another important consideration is tow vehicle tires are designed for ride comfort, which is achieved in part by allowing their sidewalls to flex.
Your trailer is a follower, which often makes tire sidewall flexing a negative. Sidewall flexing on trailers, especially those with a high center of gravity (enclosed/travel trailers) or that carry heavy loads, is a primary cause of trailer sway. Typical passenger radial tires with flexible sidewalls can accentuate trailer sway problems. The stiffer sidewalls and higher operating pressures common with Special Trailer (ST) designated tires help reduce trailer sway.
"Trailers will be more stable and pull better on tires designed specifically for trailer use. Since Special Trailer (ST) tires are constructed with heavier duty materials, they are tougher than typical passenger vehicle tires."
Also consider that Special Trailer (ST), as well as Light Truck (LT) tires are fully rated for trailer applications. This means ST- and LT-sized tires can carry the full weight rating branded on the sidewalls when used on a trailer.
However when P-metric or Euro-metric tires are used on a trailer, the load capacity branded on the sidewalls must be reduced by 9%. This means P-metric or Euro-metric tires with a maximum branded load rating of 1,874 lbs. for use on a car is only rated to carry 1,705 lbs. when used on a trailer.
Comparing the load capacities of a pair of tires of the same dimensions fitted to a single axle trailer, ST225/75R15 Load Range C-sized tires inflated to their maximum of 50 psi provide 4,300 lbs. of load capacity, where P225/75R15 Standard Load-sized tires inflated to their maximum of 35 psi would be limited to 3,410 lbs. of load capacity, a total reduction of 890 pounds.
Trailers will be more stable and pull better on tires designed specifically for trailer use. Since Special Trailer (ST) tires are constructed with heavier duty materials, they are tougher than typical passenger vehicle tires. This is a plus because trailer suspension systems are generally stiffer and less sophisticated than automotive suspension systems.
Special Trailer (ST) Tire Speed Ratings
Industry standards dictate tires with the ST designation are speed rated to 65 MPH (104 km/h) under normal inflation and load conditions.
However Goodyear Marathon and Power King Towmax STR tires featuring the ST size designation may be used at speeds between 66 and 75 mph (106 and 121 km/h) by increasing their cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.
Do not exceed the wheel's maximum rated pressure. If the maximum pressure for the wheel prohibits the increase of air pressure, then maximum speed must be restricted to 65 mph (104 km/h).
The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire.
Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.
There are differences in the driving requirements between the tires on your trailer and those on the car or light truck you use to tow it. Therefore, there are distinct differences between the way trailer tires and tow vehicle tires are engineered.
Your tow vehicle is a leader, which means traction is a key focus in the design of its tires. Traction allows your tow vehicle to accelerate down the road, turn around the corner and brake to a stop. Another important consideration is tow vehicle tires are designed for ride comfort, which is achieved in part by allowing their sidewalls to flex.
Your trailer is a follower, which often makes tire sidewall flexing a negative. Sidewall flexing on trailers, especially those with a high center of gravity (enclosed/travel trailers) or that carry heavy loads, is a primary cause of trailer sway. Typical passenger radial tires with flexible sidewalls can accentuate trailer sway problems. The stiffer sidewalls and higher operating pressures common with Special Trailer (ST) designated tires help reduce trailer sway.
"Trailers will be more stable and pull better on tires designed specifically for trailer use. Since Special Trailer (ST) tires are constructed with heavier duty materials, they are tougher than typical passenger vehicle tires."
Also consider that Special Trailer (ST), as well as Light Truck (LT) tires are fully rated for trailer applications. This means ST- and LT-sized tires can carry the full weight rating branded on the sidewalls when used on a trailer.
However when P-metric or Euro-metric tires are used on a trailer, the load capacity branded on the sidewalls must be reduced by 9%. This means P-metric or Euro-metric tires with a maximum branded load rating of 1,874 lbs. for use on a car is only rated to carry 1,705 lbs. when used on a trailer.
Comparing the load capacities of a pair of tires of the same dimensions fitted to a single axle trailer, ST225/75R15 Load Range C-sized tires inflated to their maximum of 50 psi provide 4,300 lbs. of load capacity, where P225/75R15 Standard Load-sized tires inflated to their maximum of 35 psi would be limited to 3,410 lbs. of load capacity, a total reduction of 890 pounds.
Trailers will be more stable and pull better on tires designed specifically for trailer use. Since Special Trailer (ST) tires are constructed with heavier duty materials, they are tougher than typical passenger vehicle tires. This is a plus because trailer suspension systems are generally stiffer and less sophisticated than automotive suspension systems.
Special Trailer (ST) Tire Speed Ratings
Industry standards dictate tires with the ST designation are speed rated to 65 MPH (104 km/h) under normal inflation and load conditions.
However Goodyear Marathon and Power King Towmax STR tires featuring the ST size designation may be used at speeds between 66 and 75 mph (106 and 121 km/h) by increasing their cold inflation pressure by 10 psi (69 kPa) above the recommended pressure for the rated maximum load.
Do not exceed the wheel's maximum rated pressure. If the maximum pressure for the wheel prohibits the increase of air pressure, then maximum speed must be restricted to 65 mph (104 km/h).
The cold inflation pressure must not exceed 10 psi (69 kPa) beyond the inflation specified for the maximum load of the tire.
Increasing the inflation pressure by 10 psi (69 kPa) does not provide any additional load carrying capacity.
postmandug
Member
Sun2Retire said:
That's funny. My ST tires have a speed rating letter of L. It also states right beside that 75MPH...........
Yeah ... many ST class tires today carry a L or M speed rating. There maybe a few maypops still left that carry the old 65 mph speed ratings.postmandug said:
The new Goodyear Endurance that replaces the old Marathon maypops....or Carlisle new HD that replaces the old Radial Trail ....and the time and miles proven Providers ST class tires all carry the newer higher speed ratings.
I recently had a blowout on my 2008 Gulfstream Streamlite. Only real damage was the plastic fender being destroyed. It's not available from Gulfstream. Anyone know where I might be able to find a replacement? I've tried Colaw and 5 Star with no luck.
Thanks,
Warren
Thanks,
Warren
FastEagle
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- Jan 12, 2010
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Bobtop46 said:
Very good presentation. The blue markings are as I see it.
About three years ago the China ST tire manufacturers were forced to use some sort tire markings to designate their speed restrictions. It was brought about with a threat of tariff fees for all that did not comply. Although the load range letter is the only official method to measure the ST & LT tire load capacities, the use of a service condition is allowed so the speed letter identifier can be displayed as a suffix of that method. Almost all ST tire manufacturers went with that method. However, some may mold the words right on the tire sidewall. Maxxis did not get any tariff relief and I've not seen - to date - any of their ST tires with speed letters or any other markings for speed. Regardless of what a tire manufacturer might say about adding speed it cannot be official without a starting point. The TRA says unmarked ST tires are rated at 65 MPH. There is no speed letter for 65 MPH.
