question on tire research

GrumpyandGrandma wrote:

Me Again wrote:

GrumpyandGrandma wrote:
Most RV tire issues are not due to where the tire came from, but from improper loading, under inflation and speed. 99% of all ST tires (US made included) are speed rated at 65. As to using LT on a tandem axle set-up, it is not recommended due to the side wall flex in hard turns. LT's have been known to pop off the rim in a hard turn due to the stiffer sidewall. The other big issue with ST tires is how long the unit has sat on a dealers lot (usually gravel) without moving before it is sold.

What a crock! ST tires fail at a high rate because they are a bottom tier cheaply made product, that we designed for utility trailers and local service. Some brainyact decided that one could see America with them on large heavy tall trailers.

Chris

You have your oppinon which if fine, but all you have to do is "research the facts". I camp with two very large clubs that are composed of 95% trailers and fw and the members do not have a large tire failure rate. Those that do are usually at the 5 to 6 year age range.

Here is some of the info

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.

Allan Kam, former senior attorney for the NHTSA apparently agrees in court testimony with "the crock"!!

Here's some 'research' for ya.............

Another "club" - 678 posts since 2006 and counting.
*NOT* heavy 5th wheels, but probably the lightest Travel Trailers on the market - Airstream.

Airforums on ST: "Goodyear Marathon Failures"

The crock is the standard company "line" you regurgitate - as evidenced in court testimony by GY:
"In *every* case the customers were at fault."
The tires were "run too hot, too fast, with too heavy a load, too little air, punctured and poorly repaired or they were driven over sharp objects" - and the most humorous is driven - "too seldom".

Reply (in court testimony) to that by the former senior attorney for the NHTSA = "That's absurd".

IMO - his reply indicates....."that's a crock!", ROTFL..:B

BTW - The outcome is *fact* - not opinion.
GY *lost* the crock argument and the suit.

But here's a tire *opinion*..... ST = Simply Terrible!..:(



~

Ah its fun to sit in my camp chair with the campfire illuminating the "LT" on my trailer tires while I read this continuous yammering about tires. I smile knowing I didn't have to coddle my tires to get here, didnt have to limit my speed or worry about what surface I park on or how much sun they are getting, or any of the other excuses for ST tires.

Go ahead and listen to the self made tire blog experts, and send all your money to China. The more RVs on the side of the road, the more vacancies here in the campground. I find running LT tires makes me far less "GRUMPY" :)

grumpy says wrote:
So the total miles would probably be in mid to upper 5 digit range.

Thats what I thought.
I get that many miles out of one set of LT tires on each of my Equipment and RV trailers. I have over 800k miles towing equipment/flatdeck trailers with 3.5k on up to 10k axles and 14"/15"/16" tires to make a living over a 11+ year period. Thats not counting miles pulling three different 5th wheel RV trailer up to 13k GVWR.

We all know a ST is engineered just for trailers and most folks know a LT can be used in a steer/drive and trailer position and is recommended to do so by the tire makers.
We don't see or hear stories about LT popping off of wheels unless it was severally under inflated.

grumpy says wrote:
Forgot one very important piece of the puzzle. Dexter has always said to make sure your rims are rated for the tire being installed. YOU CAN't PUT LT's on rims designed for only ST's. Something else most people don't check.

Dexter or any wheel maker does not make their trailer wheels specific for a ST tire. I'm sure the forum/trailer manufacturers/dot/Dexter/etc would like a credible link or a source for that opinion.

Good grief this is getting silly.

Me Again wrote:
Who wants to tow a trailer over 65 MPH for an extended time? Chris

Miss read what your point was, but alot of people do unfortunately.

Who wants to tow a trailer over 65 MPH for an extended time? Chris

FROM RV TIRE SAFETY, just to mention one.

For Goodyear Marathon tires only:
There is a Goodyear  Tech bulletin   PSB#2011-13 that uses information from TRA.   
The tech bulletin says that the normal max speed for Marathon ST type tires is 65 mph. This speed can be increased up to 75mph  the inflation pressure is increased by 10 psi. This new inflation can be 10 psi higher than the pressure molded on the sidewall of the tire that is associated with the tire max load.
The load does not increase beyond the load molded on the tire sidewall.
Goodyear does not support or condone operation above 75 at any time.
The trailer owner is responsible to confirm the rim is rated for the new inflation level.
While TRA indicates a further increase in speed might be achieved Goodyear has decided not to adopt this option.

GrumpyandGrandma wrote:

Me Again wrote:

GrumpyandGrandma wrote:
Most RV tire issues are not due to where the tire came from, but from improper loading, under inflation and speed. 99% of all ST tires (US made included) are speed rated at 65. As to using LT on a tandem axle set-up, it is not recommended due to the side wall flex in hard turns. LT's have been known to pop off the rim in a hard turn due to the stiffer sidewall. The other big issue with ST tires is how long the unit has sat on a dealers lot (usually gravel) without moving before it is sold.

What a crock! ST tires fail at a high rate because they are a bottom tier cheaply made product, that we designed for utility trailers and local service. Some brainyact decided that one could see America with them on large heavy tall trailers.

Chris

You have your oppinon which if fine, but all you have to do is "research the facts". I camp with two very large clubs that are composed of 95% trailers and fw and the members do not have a large tire failure rate. Those that do are usually at the 5 to 6 year age range.

Here is some of the info

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.

This is the first I have seen anyone claim that overinflating a ST tire will increase its speed rating. Please give a link to the *manufacturer's* site that says this. Sorry, that's a bit hard to believe.

Of course heavier trailers will have more failures. Look at the math:

My trailer weighs 13,500 lbs. The weight on the trailer axles is 11,300 lbs (CAT scale weight). I have Towmax "E" tires, weight rating 3,500 lbs. Ok, 11,300 / 4 = 2,875 lbs. That is 82% of the rated capacity of each tire. If I inflate to 80psi (which I do), then I have close to a 20% margin between actual and rated weight. If you consider that all 4 wheels carry more or less than a quarter of the weight, it is unlikely the variance will be more than 630 lbs (the difference between tire rated load and computed weight). So, I feel fairly safe with the Towmax, ST's at least for now.

Many rigs are carrying too much weight. When you are over 90% of rated capacity and under inflate by even a few pounds, the tire is bearing more than its rated load. Driving over 65 generates heat and stress that will lead to failure at some point. The key is to get your rig weighed fully loaded and calculate the tire load. Also, we have a TPMS and watch temp and pressure throughout the trip. We never leave without assuring we are at 80 PSI.

Could we still have a failure? Yes, of course. But we are doing all we can to avoid it. Next year, if we can afford it, I plan to change to 17 1/2" wheels and Goodyear 114's. While technically LT's, they are rated for use on trailers. They are G rated so there are more ply's than on my "E" Towmax. Since they are technically LT's, they have a speed rating of 75 MPH. We will NOT be driving that fast. Currently we stay at 60 or less. If we upgrade, I can see doing 65 sometimes. It's unsafe, according to Ford, to tow any faster than that.

JIMNLIN wrote:
The issue with Mark Polk isn't speed/overload or inflation but rather his blogs on tires in the past have said LT tires can't be used on trailers or ST have a stiffer sidewall or Discount Tire nonsense/etc;

Comments like that tells most folks with trailering experience he has no idea what he's talking about.
Mark has pushed that agenda for years although he might have become better educated on the subject and now preaches a different tune.

Most folks with multiple tire issues have upgraded to a better class/brand of tire or a higher rated tire and had no more issues.

Just curious but your pretty vocal about the ST vs LT issues.
How many years and how many miles and how many heavy trailers have you towed ??

As I stated earlier have been Rv'ing since 1973 and towing travel trailers and fifth wheels since 1977 until we traded for the mh in 08 and we are going back to a FW in November. As to miles look at my sig. We have hit every state numeous times with the exception of 3 and have also traversed all of Canada and never had a ST tire blow, So the total miles would probably be in mid to upper 5 digit range. I also meeti every summer with a group of 100-200 who mostly tow trailers and fifth wheels and there may be one or two who had tire failures along the way. Yes it happens, but based on the number of ST's on the road it is not extreme.

The info I've gathered is by researching as much as possible over the last 41 years since I don't want my family in jeopardy. I also managed a 50 vehicle fleet for 15 years and personally discussed the issue with tire reps and they all say ST's are engineered for trailer and LT's are engineered for trucks. LT's have been know to pop off the rim in tight turns due to the stiff side walls so nothing is perfect. As a matter of record MICHELIN just had a major recall for tires on the E-450 chassis used for MH's.

What I have said from the beginning and I will say it again.... If you overload and run a tire underinflated, too fast for it's rating or older than 5-6 years (especially if they sit for long periods) they will fail and that is what you will read on every tire site.(Mark Polk, Tire Safety or whoever) I see it everytime we travel people towing at 75 or faster and they are just asking for trouble or they are on the side of the road with a flat.

Forgot one very important piece of the puzzle. Dexter has always said to make sure your rims are rated for the tire being installed. YOU CAN't PUT LT's on rims designed for only ST's. Something else most people don't check.

GrumpyandGrandma wrote:
Tire Safety says exacty the same things I have pointed out about failures:
LOAD, INFLATION and SPEED, which is the same thing Mark Polk said as well, but someone keeps saying that is all BS and it is not. If you run ST's or lT's and are under inflated and overloaded you will probably have a problem. Also as I mentioned in the begining MICHELIN XZE truck tires are rated at 75 so GM governed the KODIAKS at 75 the XPS tires are as well. So if you are in a state with an 80 mph speed limit you stay at 75.

Roger also puts a big "BUT" in his column about the switch to LT's it not just a matter of size for size you have to research the load rating.


The problem is not ST or China it is failing to follow what the tire sidewall says no matter what brand or type.

I will dispute you on that last statement. I've known several people with experience with manufacturing in China, and they will do what they can to cut corners and build and sell junk whenever they can. They will use non-standard manufacturing methods and sub-standard materials. When their customers complain, the company simply changes names and starts all over again. They also play shell games with different plants and will showcase production at one plant when an inspector shows up, but produce double the junk at some plant across town that is never seen. I =also= blame the RV manufacturers for using the absolute cheapest tires they can.

Lyle

The issue with Mark Polk isn't speed/overload or inflation but rather his blogs on tires in the past have said LT tires can't be used on trailers or ST have a stiffer sidewall or Discount Tire nonsense/etc;

Comments like that tells most folks with trailering experience he has no idea what he's talking about.
Mark has pushed that agenda for years although he might have become better educated on the subject and now preaches a different tune.

Most folks with multiple tire issues have upgraded to a better class/brand of tire or a higher rated tire and had no more issues.

Just curious but your pretty vocal about the ST vs LT issues.
How many years and how many miles and how many heavy trailers have you towed ??