RE: China Bombs Got Me
JJBirish,
There are a number of items in your post I would like to comment on, but in the interest of brevity, I’ll only focus on only one – one that I think is the key difference in our understanding of the DOT testing requirements. Perhaps we can find common ground.
First, I hope it is clear that tire “size” plays a large role in the rated load of a tire regardless of tire type. Put another way, larger tires have more rated load than smaller tires – all other things being equal. In trying to compare rated loads of tires of different types, we need to also compare tires of the same “size”. I put the word “size” in quotes because the letters in front of the numbers (in my view) also are part of the “size” as they delineate the type of tire involved.
When it comes to comparing LT tires and ST tires, there is a problem – very little commonality in “size”. I’m going to chose a “size” that is common to both LT’s and ST’s – 235/85R16 Load Range E:
ST235/85R16 LR E: Max Load 3640# at 80 psi – with a speed restriction of 65 psi.
LT 235/85R16 LR E: Max Load 3042# at 80 psi – and a common speed rating is Q = 99 mph.
Notice the difference in rated loads and speed restrictions. I hope it is obvious that a tire’s speed capability is inversely related to its speed – that is, the higher the speed, the less load it is capable of carrying (all other things being equal) – and that is reflected above.
So let’s take one of the DOT required LT tests and see how that plays out as far as load goes. How about this one:
.....=================================================
Category B Endurance Test:
(LT "E" tire at 50 PSI)
4-hour test: 85% of tire maximum load rating at 75 MPH
6-hour test: 90% of tire maximum load rating at 75 MPH
24-hour test: 100% of tire maximum load rating at 75 MPH
……..
For an LT235/85R16 Load Range E, the last step is 3042# load.
But for an ST235/85R16 Load Range E, that’s only 84% of its rated load. Or put another way, it is only 110% of the maximum load at 50 psi.
I think an ST tire can survive that last step.
Comments?
RE: China Bombs Got Me
Sorry for the severe truncation, but I only wanted to comment on one part:
.....The real problem is the standard for DOT certification that sets minimum requirements for the tires safety… those minimum standards are the target that many aim for and all must meet….......
I disagree. I am of the opinion that the standard DOT testing requirement doesn't mean the tires are safe - meaning relatively free of structural failure. In fact, it has been recognized within the tire industry that tires have to greatly exceed the DOT minimums in order to perform up to consumer satisfaction levels of nearly zero structural failures.
And just so you know, it appears that consumers expect tire failure rates to be less than about 0.01% - 1 out of 10,000 and the value has been dropping over time. You can not get that if you only meet the minimums.
I am also of the opinion that ST tires can easily pass the LT tire DOT minimums - and vice versa. Where I think the problem lies is inexperience with what levels are acceptable in the marketplace. Many manufacturers think that passing the minimums is enough to assure the product (and this is not just about tires) is good enough - and that is just not so. While price drives a lot of initial acceptance, it is difficult to overcome a poor quality reputation.
I'm afraid the Chinese have just started to learn this lesson - and in the case of tires, it requires a lot of effort (and cost) to figure out how get to that higher level. They will get there eventually, but by then some other country will have entered the market with low ball pricing (and poor quality). This is a pattern that I first saw with Japanese products in the 1950's and 60's - and continued with the Mexicans and the Koreans. I expect India to be next.
RE: China Bombs Got Me
I see this as a multi-level problem:
1) We know that people don't do a good job of checking tire inflation pressures. We can verify that by looking at the results of surveys taken of tires in use.
2) We also know that trailer manufacturers haven't done a good job of supplying tires that have enough rated load carrying capacity. We can verify that by looking at the results of surveys taken of trailer in use - usually done at the same time the tire pressure loads surveys are done.
Side note: Either the trailer manufacturers need to do a better job of estimating the actual loading their trailers experience - OR - they need to do a better job of selecting tires that are rated to carry the loads the tires are being subjected to - or both! (Personally, I vote for both.)
Further, there seems to be a misconception that a) tires are loaded evenly (based on many many comments about weighing the trailer then dividing by 4 to get the tire load) and b) that the tire load tables are recommendations (It says "maximum load" for a given inflation pressure)
3) The tires themselves need to be further developed. I note with interest that most of the large tire manufacturers do not produce ST type tires. The only large manufacturers of note are Goodyear and Cheng Shin (Maxxis).
So I think it is fair to ask about the weight of the trailer (See #1 and #2 above). I see this as less a criticism of the owner and more a step in helping sort out what the cause of the tire failure was - and we know that there is some overloading taking place.
It's also fair to criticize the tire manufacturers.
It's also fair to criticize the trailer manufacturers.
I do not think there is a single answer to the broad question. I'll bet that the reason NHTSA hasn't done anything about ST tires (that we know of) is that they are aware of the loading issues and they are aware that very few trailer tire failures lead to personal injuries - and since "Traffic Safety" is what NHTSA is all about, the lack of personal injury reports doesn't make much of a case for their intervention.
So I say again: If you have a tire failure, report it to NHTSA. They will not act unless there are a large number of reports.
RE: China Bombs Got Me
Are we going to go through this again? I'm getting pretty tired of having threads closed because people feel they need to discredit other people by accusing them of promoting particular kinds of tires.
For heaven's sake, let's stop the personal attacks and stick with discussing the topic.
RE: air?
Word of caution:
The load tables being referred to are NOT recommendations. They list maximums (loads) or minimums (inflation pressure) Many vehicle manufacturers specify inflations pressure significantly higher than needed for the GAWR - and I think there is a lesson to be learned there.
I recommend that tires should be inflated such that there is a 15% reserve (unused) load carrying capacity. Safety first.
RE: Sorry for another tire post, but this has different twist.
And here is the reason why "dualed" tires have less load carrying capacity than "single" tires.
Differences in tire diameter are going to affect how much load each dualled tire carries - the larger diameter tire carrying more. In order to account for these small differences - and to make sure a given tire isn't overloaded - the load carrying capacity of a dualled tires is reduced about 9%.
This applies to any tire that is dualled up - light truck, medium truck, heavy truck, earthmover - but not all of those are designed to be dualled up. It does not apply to tires that are not designed to be dualled up - passenger car, ST, motorcycle, agricultural, etc.
Oh, and "tandem" axles are paired axles (right next to each other), where a "dualled" axle has 4 tires on it (2 on each end). Tandem axles are considered "singles" from the tire's perspective.
RE: Crazy steering wobble/shake
A couple of thoghts:
I had a discussion with a suspension engineer at Ford. He told me that vehicles with high caster angles tend to develop these "death rattles". Jeeps have been pointed to as having this problem - and they have high caster angles. So do some Ford trucks.
I've also picked up that it doesn't take much wear on components to turn a vehicle into one that has this problem - small enough wear that most shops would say the vehicle is fine.
So I'm curious if this apples here as well.
RE: Tire Info
And just an FYI:
Radial tires are generally built with 2 radial plies (bead to bead which includes the sidewalls) and 2 additional steel plies under the tread. Sometimes there are nylon (or generic name polyamide) cap plies ( 1 or 2).
This is true for passenger car tires, light truck tires and ST tires.
Variations: Small Passenger car tires may need only a single ply for strength purposes.
Large truck tires (over the road size) are frequently made with a single steel body ply. These tires usually have additional plies in the belt area that function like cap plies.
Some off road LT tires may use 3 sidewall (body) plies. This is more for damage resistance than strength.
US regulations require the construction to be written on the sidewall of all street tires. It will appear in the form:
Sidewall: 2 plies polyester
Tread: 2 plies polyester, 2 plies steel, 1 ply nylon.
(or what ever the construction is)
RE: Follow up to blow out (there is a tire question at the end)
First, you can NOT prevent. You can only reduce the risk. The best way to do that is:
1) Weigh the trailer fully loaded. Weigh each wheel position and determine the worst case. I am of the opinion that you need to have at least a 15% un-used load carrying capacity in your tires. If you don't, fix that by going larger or increasing the inflation pressure.
2) Check the pressure in your tires BEFORE every move. Sometimes that will mean daily.
3) Inspect your tires BEFORE every move. Use gloves and rub the tread around the circumference. Any tires with bulges should be replaced IMMEDIATELY!
4) During the inspection, look for cracking. When it gets excessive, replace the tires - REGARDLESS of how old they are or how little wear they have.
5) Replace your tires based on age. There is some disagreement as to what that limit should be, but for trailer tires, 5 years is a common value.
Now to answer your questions: Covers will help. Keeping them fully inflated will also help.
RE: tow vehicle tire air pressure/load quandary
If you will allow me, I'll give some insight into what the vehicle manufacturer does regarding the pressure that is listed on the vehicle tire placard and in the owners manual.
Different vehicle manufacturers use different methods to arrive at the tire pressures, but once they get there, they select springs, shocks, and sway bars based on that pressure.
Then they test. They test the vehicle in all configurations - fully loaded, empty. If the owners manual calls for a different pressure when empty, they will have tested it.The handling tests are quite severe - commonly called limit handling.
So if your vehicle owners manual does NOT call for a different pressure when empty, the vehicle manufacturer probably did not test that condition.
We know that a tire's spring rate changes with pressure - and changing pressure that changes the handling balance - the understeer/oversteer characteristics.
I am of the opinion that the vehicle manufacturer's specifications should be followed because those conditions are known. Anything else is unknown.
RE: BlowMax Tires
According to their website specs they are 31.5" in diameter, the same diameter as a ST235/80-16.
CAUTION: The specs on Goodyear's web site might be wrong. Every other tire they make in that size is 1" larger in diameter than what is quoted for the G614.
RE: blown tire collision or comprehensive
A couple of thoughts on tire failures:
First, these are covered by the comprehensive. not the collision part of the vehicle insurance.
Second, sometimes tire failures can be attributed road hazards - and the tire manufacturer may deny the claim. In that case, the vehicle insurance covers it under the comprehensive part.
In many cases, it becomes easier to file a claim with the insurance company and let them deal with the tire manufacturer.
- and it is my understanding that claims filed under the comprehensive coverage will not cause your insurance rates to go up (unless you file a bunch of them!)
RE: trailer tires
Just an FYI:
As a tire engineer, I have always wondered why wheels don't have max pressure limitations stamped on them. I can understand that there is a limited amount of space on a wheel and there is more important info. But I have seen so many cases where there is a maximum load and still plenty of space.
I mean, tires have this info stamped on the sidewall, so why not wheels? Yes, I know tires are required by government regulations to have this info, but why not wheels? If max pressure is so important, why aren't there the same sort of regulations for wheels?
In my quest for the answer, I searched out people who design wheels. Not people who sell them, the guys who specify what materials go into wheels - what kind of steel, how thick, etc. So far I have run across 2 people who fit this description - and are willing to discuss the issue. They both said that the stresses applied to the wheel by the load is so much greater than the stresses from inflation pressure, that you can ignore pressure. Put a different way, differences in inflation pressure doesn't cause enough difference in stress to worry about - and that's why wheels don't have maximum inflation pressures stamped on them.
Just recently, a paper was given at a conference on computer modeling. The paper was about applying a particular stress analysis software to wheel design. While the paper wasn't specifically about the results obtained, it did give some insight into the subject. What I found interesting was that while it was clear that the load on the wheel was important, inflation pressure wasn't mentioned at all. I take this as further confirmation of my previous conversations.
I interpret all this to mean that if a wheel doesn't have a maximum pressure rating, that the maximum allowable pressure is more than what the tire's maximum would be - so there isn't a problem.
I also interpret this to mean that given the choice, it would be better to use more inflation pressure (even more than the maximum listed on the wheel), rather than use the lower pressure that seems to be contributing to tire failures. Put a different way, this is about which risk is greater - and the wheel seems to less sensitive to inflation pressure than the tire is.
RE: tires
I'm not so sure you in fact gain that extra protection from an ST tire underinflated by 15 to 20%.
It's not "just been heard", but I have yet to see a manufacturer or knowledgeable source recommending inflating an ST tire for anything under the max pressure listed on the side wall.......
Larry
A couple of thoughts:
First is using the maximum inflation pressure listed on the sidewall of a tire? It depends.
When we talk about cars and light trucks, there's a vehicle tire placard that lists the original tire size and proper inflation pressure for that size. If you have one of those vehicles, that's what you should use (unless you've changed tire sizes, then the pressure has to be recalculated)
If you have a recently built travel trailer, it also should have a vehicle tire placard. I do not think you will find any that do not use the maximum pressure written on the tire, because trailer manufacturers are well known for using the smallest tires they can. So many people say you should use the maximum, including tire manufacturers, but this isn't quite accurate. If you've oversize the tires on your trailer, then the maximum MIGHT not be appropriate - and to be able to tell, you need to know the load on the tires.
I hope this clarifies things.
RE: Maxxis trailer tires
And just an FYI:
The difference between a Load Range D and a Load Range E (what people are referring to here as 8 ply vs 10 ply - incorrectly I might add) is small enough that it has neglible affect on the running temperature. Check what is written about the construction on the sidewall of otherwise identical tires and they will both read the same. The ply material is ever so slightly heavier in a LR E, but not enough to worry about. The rest of the tire completely overwhelms what small differences there may be.
RE: Max tire pressure vs Load on tires
I recently had new tires installed on my 5th wheel. I then had the rv weighed. It was weighed one wheel at a time. I know what the weight is on each wheel. Should I inflate the tires to the max stated on the tire or base it on the weight on the wheel?
My opinion is that a tire needs to be inflated such that the load carrying capacity is 115% of what the load table says is the minimum. You'll find that many vehicle manufacturers use this value 9or similar values) - especially the ones that don't seem to have tire issues.
RE: Siping tires
The great thing about forums is you can always get the advice you were hoping to get to back up your own judgement.
Take your pick
it also increases friction, which increases heat and decreases fuel mileage.
the tires run cooler snd last longer summer or winter.
:B
Don't you just love tire threads? They are so entertaining! Any answer you want!
RE: Insurance adjuster/policy question (trailer damage)
Grunt,
You are overcomplicating this. I get involved with these kinds of things on a regular basis and here's the skinny.
1) If the tire manufacturer has agreed to pay, then they owe you the 3 deductibles. Follow their procedures - which ought to be estimates, and the insurance adjuster's estimates ought to be adequate.
2) While the bank holds the lien, you own the vehicle. You can do what you want without the bank's approvel. Keep them out of the loop. It will just compliacte things.
3) Yes, there are 3 separate incidences. Yes, they have a common theme, but they occurred at different times. Besides, the tire manufacturer has agreed to settle the claim, so you shouldn't worry about them.
4) Your willingness to do the work yourself shouldn't be reflected in what the insurance company does. If they will only pay the guys that repair the vehicle - so be it. But if they are willing to give you a check, then you can repair it yourself - and YOU would then be compensated for the time it takes you to do the repairs.
So keep it simple.
RE: PLEASE HELP ON TIRES AND AXLES
I have a fiver that weighs about 11,000 pounds dry. It has two axles. The tires are ST225/75R15, D rated, 2540 pounds. Most of the tires this size are out of china. I want to go to a 16" tire with Michelin Ribs with a E rating. There is plenty of room on the front axel on top and sides. On the driver side rear axel the size tire on it now is 5/16 from a rod that operates the slide. It has been like this since I got it new. The fiver probably has 12,000 miles on it with no issues.
My question is if push comes to shove would it be safe to put 16" tires on the front axle and a 16" on the passenger side of the rear axel with a 15" on the driver side where it is so tight? Or maybe 16s on the front and15s on the rear? From the center out you are only talking about 1/2inch. Also how would this affect the towing on the fiver.
Also in the past on other smaller trailers I used maybe a 1/2 inch of flat washers on the lug bolts with double lug nuts to move the entire rim and tire out away from the springs or frame.
I am scared to death of these Chinese tires. How about some help on this. I thank all of you.
Well,
You could go to LT225/75R16's and the only clearance issue you'd have to worry about is the diameter. No need to washers to change the offset.
Oh, and mixing sizes is a terrible idea. It's bad enough that there is going to be differences in the loading of individual tires, but differences in diameter is going to make this much, much worse.
