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Old 03-14-2015, 12:17 PM   #29
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Quote:
Originally Posted by lahrfarm View Post
So why LT tires?
Quote:
Originally Posted by lahrfarm View Post
Is it a wieght rating thing or a speed rating over ST. You can get a higher weight in ST-15's, Powerking STR for one
Many people, me included, would NEVER use or recommend ST tires on an Airstream. Any tire stamped with "FOR TRAILER USE ONLY", as all ST tires are, have no place on an Airstream in my opinion. The ST tires are fine for a utility trailer, but not much else in my opinion. P tires and LT tires can carry their load at a much higher speed than an ST tire. Nearly all ST tires are load rated at 65 MPH. The Maxxis is an exception.

Quote:
Originally Posted by BoldAdventure View Post
Top is right, but I found that I had special order most of those. If I walk into a Discount Tire, Sears or Costco anywhere in the nation chances are they'll have the Michelin LTX in 16's. For us as full-timers on the road, having something that is everywhere is more ideal than a tire we would have to special order to get on hand.
There is a spare tire carrier to help in those situations If you have the best quality tires, like you do, the likelihood of being at a tire shop with a tire problem is pretty slim.

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Originally Posted by dznf0g View Post
My answer to post 22: Higher load capacity in a non-ST. I won't discuss the pros and cons of an ST...it has been beat to death. You can search the threads. For me, I prefer an LT and I have to have an LRE with my weight.

For OP (bertheep), I am not sure how much weight is on your axles, fully loaded with gear and fluids....etc. I suspect you are marginal for a LRD tire after the de-rating for a non- ST tire, but it appears the Nokian would certainly work....maybe the Goodyear cargo. I would definitely weigh your trailer...fully loaded and then multiply the published tire capacity by .85 and see where you are.
The Euro size Nokian does not need to be derated for use on a trailer. Only P tires need to have their load capacity derated 10% when used on a trailer.

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Originally Posted by dznf0g View Post
Wait, I just noticed a couple of Tops listings are 235s. Didn't I see on here somewhere that 235s don't fit up under the wells? ...or was that 235 75 R16s?
I have 235/75/15 Michelins on my trailer and they fit just fine and dandy. I don't recall anyone using 235/75/16. Maybe you are thinking of LT245/75/16 or ST235/80/16?
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Old 03-14-2015, 12:22 PM   #30
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I really don't recall the fitment issue, Lance. Frankly, once I got my LTs in 2011, I quit reading the fruitless debate...it was all a rehash.....except for the two members who are tire experts (I did read the de-rating posts)...and I believe one of them is a proponent of de-rating LTs as well. Since I assume they are more expert than I, I will de-rate per their recommendation. If I misunderstood that recommendation, perhaps they will clarify.
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Old 03-14-2015, 03:18 PM   #31
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Originally Posted by dznf0g View Post
...and I believe one of them is a proponent of de-rating LTs as well. Since I assume they are more expert than I, I will de-rate per their recommendation. If I misunderstood that recommendation, perhaps they will clarify.
You're thinking of :

Quote:
Originally Posted by Tireman9 View Post
Passenger tires must have their load capacity derated by dividing by 1.10 when being used in trailer application.
No such de-rating need be applied to LT tires.

Now a 15% reserve load i.e. the actual load is no more than 85% of the load capacity of the tire when inflated to a specified level.

I have posted the technical reasons for Running multi-axle trailer tires at the inflation on their sidewall.

Fictional example with made-up numbers

Measured loads on a trailer
RF 3200 LF 2700
RR 2900 LR 3100

1, Front axle use 3200# consult Load Inflation table and confirm the tire can carry at least 115% of 3200 or 3680 when inflated to the tire sidewall max
2. Rear axle use 3100# so can the tire carry 3565# ?
3. You confirm your 345/65R17 LR-E tires are rated for 3700# at 80 psi
4. You are good to go when you inflate all your tires to 80 psi.


BUT lets say your tires are 300/75R16 LR-D at 65 psi which are only rated for 3000#
If you were your brother in- law who refuses to learn the actual individual tire loading you might think all is OK as the CAT scale weight reading is 11,900 or 2975# per tire. He also doesn't think any reserve load is needed and he also doesn't like the rough ride he gets with 65 so reduces his inflation just a bit to 60 psi as that is "close enough".
Is it any surprise that late in the summer after never checking his tire pressure he has two tread separations? Of course the failures are the tire's fault.
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Old 03-14-2015, 04:39 PM   #32
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Enough already

This thread has gotten out of hand and strayed far from my original post. Thanks to all those who addressed it directly.
Bert
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Old 03-14-2015, 07:51 PM   #33
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Guess I'm having trouble differentiating between the term derate (10%) and reserve load (15%)????
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Old 03-15-2015, 07:54 AM   #34
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Originally Posted by dznf0g View Post
Guess I'm having trouble differentiating between the term derate (10%) and reserve load (15%)????
Perhaps this will help.

When tires are designed, the starting point is the tire load tables. These tables not only standardize the load/inflation/dimension issues for vehicle manufacturers - so they can chose a tire and have confidence that putting another brand on isn't going to cause an overload situation - but also for the tire manufacturers to design tires.

To develop these tables, the service conditions are also considered.

Taking a Passenger car type tire as an example, I think it is easy to see what "Passenger Car Service" means - highway speeds, highway surfaces, softly sprung, low inflation pressure, etc. But in order to make a P type tire suitable for Light Truck usage (which is defined as application on a pickup, van, or a trailer), the load table gets modified - and rather than publish a whole new table, the instructions are to derate the tire by 10%. When that is done, the tire has a new "standard".

By contrast, the load tables for LT tires are specifically developed for Light Truck Service, so the load table is directly applicable.

By further contrast, ST tires have an additional restriction that LT tires don't have - 65 mph speed limitation - and that results in a different load table. If one were to compare the load tables, one would find the loads on the ST tires to be higher than for the same size LT tire.

Now let's move onto reserve load. This is the application of the idea that it is better to use equipment much higher rated than the situation calls for.

For example, if a trailer is going to need 5,000# axles, it would be better to use 6,000# axles. What normally happens is this sort of thinking is done by the design engineers and is invisible to the end user.

In the same way, a tire ought to be specified such that it isn't overloaded, and some distance away from being overloaded. That's where that 15% comes in. If things were working as they should, one wouldn't even be aware that this was taking place. One would use the tire size and the inflation pressure specified on the vehicle tire placard. Passenger cars is a good example.

Unfortunately, things don't always work as they should. Some trailer manufacturers didn't do a good job of sizing tires and in order to make up for that, you have to do what should have been done before you bought the trailer - and that is size the tires to fit the job.

I had a professor who taught engineering design, and he said "Over-design / Under-utilize!" That is what the 15% reserve capacity is all about - good engineering practice.
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Old 03-15-2015, 08:46 AM   #35
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my simple take: De-rate is a DOT therm and if your tires derated maximum is equal or over your tagged axle load you get a ticket. Reserve load means that your are running under the max rated load for the tire that should give you some safety margin.

I have no idea if that means that you need to add the two together and stay 35% under the number on the tire or if you are 5% under the max with the 10% derate (15% below the tire max) is that enough safety margin? I suspect if you snuck a ST tire into a test for a LT tire it would not pass at its ST rated load.

I seem to have no access to the mysterious "load tables". My retired tire engineer friend just said that "most properties of a tire improve with inflation".
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Old 03-15-2015, 08:55 AM   #36
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Quote:
Originally Posted by Top View Post
Here are a few 15" LT tire choices.



235/75/15 LRE #2760

Nokian Rotiva AT-



225/70/15 LRD #2,470

GoodYear Cargo G26-



LT235/75/15 LRD #2,335

Pirelli Scorpion ATR-



LT215/75/15 LRD #2,094

GoodYear Wrangler HT-



GoodYear Wrangler AT/S-



7R15LT LRD #2040

Yokohama RY 215-



Now, if you have to have a Michelin LT tire, that is when you must move to 16"


Michelin LTX 235-75-15. #2183

I think I'm going with these soon. I have a 05 safari 25, there are posts of guys running these with very good results. I'm not sure how much more a 28 weighs, but they may work for you. Safari's are about 1000 pounds lighter than others. Not sure why, maybe cheaper cabinets or fewer bells.



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Old 03-15-2015, 09:06 AM   #37
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I found this.Click image for larger version

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ID:	234210


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Old 03-15-2015, 10:16 AM   #38
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"Michelin LTX 235-75-15. #2183"

I think it is a P235-75-15XL.

That is what I run on my 25' model.
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Old 03-15-2015, 10:22 AM   #39
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Quote:
Originally Posted by Bill M. View Post
"Michelin LTX 235-75-15. #2183"

I think it is a P235-75-15XL.

That is what I run on my 25' model.
They are P type tires. They are very good tires for a lot of Airstreams. I have them on my 1972 Ambassador. They have a "derated" capacity of 1985lbs when used on a trailer. The same capacity as an LT235/75/15 LRC. They are not, however, true LT type tires.
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Old 03-15-2015, 01:58 PM   #40
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Michelin LTX 235-75-15. #2183

I think I'm going with these soon. I have a 05 safari 25, there are posts of guys running these with very good results. I'm not sure how much more a 28 weighs, but they may work for you. Safari's are about 1000 pounds lighter than others. Not sure why, maybe cheaper cabinets or fewer bells.



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Highway Rib Summer light truck tires are for drivers who want a combination of heavy-duty load capacity, even wear and low noise along with traction on dry and wet roads. Sometimes used as Original Equipment (O.E.) on medium and heavy-duty 2WD trucks, vans and pickups, Highway Rib Summer tires are not intended to be driven in near-freezing temperatures, through snow or on ice.

I was looking at the Goodyear rib, and this is what it said. Is the traction issue a problem for trailers?



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Old 03-15-2015, 03:35 PM   #41
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Originally Posted by CapriRacer View Post
Perhaps this will help.

When tires are designed, the starting point is the tire load tables. These tables not only standardize the load/inflation/dimension issues for vehicle manufacturers - so they can chose a tire and have confidence that putting another brand on isn't going to cause an overload situation - but also for the tire manufacturers to design tires.

To develop these tables, the service conditions are also considered.

Taking a Passenger car type tire as an example, I think it is easy to see what "Passenger Car Service" means - highway speeds, highway surfaces, softly sprung, low inflation pressure, etc. But in order to make a P type tire suitable for Light Truck usage (which is defined as application on a pickup, van, or a trailer), the load table gets modified - and rather than publish a whole new table, the instructions are to derate the tire by 10%. When that is done, the tire has a new "standard".

By contrast, the load tables for LT tires are specifically developed for Light Truck Service, so the load table is directly applicable.

By further contrast, ST tires have an additional restriction that LT tires don't have - 65 mph speed limitation - and that results in a different load table. If one were to compare the load tables, one would find the loads on the ST tires to be higher than for the same size LT tire.

Now let's move onto reserve load. This is the application of the idea that it is better to use equipment much higher rated than the situation calls for.

For example, if a trailer is going to need 5,000# axles, it would be better to use 6,000# axles. What normally happens is this sort of thinking is done by the design engineers and is invisible to the end user.

In the same way, a tire ought to be specified such that it isn't overloaded, and some distance away from being overloaded. That's where that 15% comes in. If things were working as they should, one wouldn't even be aware that this was taking place. One would use the tire size and the inflation pressure specified on the vehicle tire placard. Passenger cars is a good example.

Unfortunately, things don't always work as they should. Some trailer manufacturers didn't do a good job of sizing tires and in order to make up for that, you have to do what should have been done before you bought the trailer - and that is size the tires to fit the job.

I had a professor who taught engineering design, and he said "Over-design / Under-utilize!" That is what the 15% reserve capacity is all about - good engineering practice.
So if you want 15% reserve on a p rated tire on a trailer, you shouldn't load beyond 75% of max sidewall stated load at max sidewall pressure?
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Old 03-15-2015, 03:52 PM   #42
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I run six of the Maxxis UE-168 Bravo tires in 235/75-15Q D Load rating (2337lbs capacity per tire) on my 34 footer and have had great success with them for the past 25,000 miles.

Maxxis used to make a UE-168 Bravo in 225/70-15 that was E rated. It looks like they've discontinued that one.

I stumbled onto Maxxis by chance, but can say nothing bad about them. I am getting due, age wise, for a new set.

I'm a huge Michelin fan. But, if I can stick with a good 15" and not have to buy six new wheels, I will probably go that route. I see another set of these UE-168's in my future.

http://www.maxxis.com/catalog/tire-2...-ue-168%28n%29

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