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SteveH · 12-11-2013, 08:00 PM

I tow in cruise control also, but only on flat ground, on interstates, with low traffic. Anything else is either not safe, or costs fuel mileage, IMHO.

Lance M · 12-11-2013, 08:02 PM

Some 15" LT alternatives to ST tires.
There are these GoodYear Wrangler LT 215/75 15 LRD

or these Pirelli LT 235/75 15 LRD
Provided they meet your loading needs.

SteveSueMac · 12-11-2013, 08:07 PM

Quote:

Originally Posted by Top

There are also these GoodYear Wrangler LT 215/75 15 LRD

Provided they meet your loading needs.

I think you need the 235s right? They would have the same capacity as the derated Michelin p tire.

m.hony · 12-11-2013, 08:19 PM

I think the Goodyears are ST 225/75R15- but I could be wrong.

Lance M · 12-11-2013, 08:35 PM

Quote:

Originally Posted by SteveSueMac

I think you need the 235s right? They would have the same capacity as the derated Michelin p tire.

The capacity on the tire GoodYear LT 215/75 15 LRD is 111 pounds more than a derated (for trailer use) P 235/75 15 XL.

The Good Year Wrangler HT I linked is a Light Truck (LT) tire.

Steve & Mary · 12-12-2013, 03:08 AM

Nearing retirement now I will move up to the 16 inch wheels and Michelin tires on our Classic 31. After having a GYM tire fail and lead to $7k worth of trailer damage I decided then I would not have another ST tire on my trailer until Michelin started building one. Goodyear paid our damages but we were still out of the expense of two trips from south La. to Oklahoma City for repairs. At the time I didn't want to move up to the 16's since we would only be doing short local pulls. So I went with a 15 inch LTX 235 Michelin which put us within the tires rating as long as we didn't load the trailer. I've had NO issues with the Michelins. Now I want that extra tire capacity and plan to go with the SenDel wheels and 16 inch Michelin LTX tires. I'm just shopping for a good deal :-)

Wazbro · 12-12-2013, 09:14 AM

Quote:

Originally Posted by m.hony

Maybe everyone doesn't need 16" wheels and tires- Maybe I don't-
Maybe people who boondock need 16" wheels because they have more batteries, solar, onboard water? Maybe they are more likely to approach the 10,000# GVW? I never will.
My trailer is probably 7,500# on the tires while parked because some of the weight is on the tongue, just like when hitched to the truck- only difference is whatever weight is transferred to the front axle of the truck when hitched-
Also, the 65 limit on the sidewall doesn't bother me as I won't be exceeding that anyway.

Someone posted on another thread that you are required to have tires that are rated to carry as much as the axles, I don't know if this is true. If true and you have 5000 lb axles you would need tires rated at least 2500 lbs each regardless of load.

The chances of someone checking would be quite low, unless you were in a bad accident.

m.hony · 12-12-2013, 10:04 AM

They build and sell the trailers every day with these tires...
I would think if there is a liability issue it would fall on the manufacturer...

switz · 12-12-2013, 10:19 AM

As perceived adults, we are held accountable for our decisions whether the results are good or not so good.

Those that don't want 16" Michelin tires and wheels, don't buy them. It is your trailer and put whatever tire and wheel you want on them. If there are ever any issues that are not so good, then live with the results of your decision. End of story.

The tire threads reflect the experiences of folks with various tire and wheel combinations and their thought processes involved to switching from the OEM tires (and wheels) to something else.

I really appreciate the exchange of ideas that helped guide my decision making process from which model of Airstream to consider to what goes inside it or supports it.

If a private vehicle were stopped by DOT, they do check axle capacity and tire capacity and the loaded weight of the vehicle in question. They look for the weakest link in the support chain to see if the load support system has the proper load carrying capability. It just makes sense to me to have tires rated at or higher than the axles even if the vehicle is never loaded to it's maximum GVW.

YMMV (your mileage may vary)

Ridgerunner3 · 12-12-2013, 11:31 AM

Quote:

Originally Posted by Thomas_G

I know I have heard not to tow on cruise but does that hold true for flat drives? I can understand hilly roads but flat highways seem like it would be okay.

I once had a 2000 Ford F-150. If I remember correctly, the owners manual for that truck said to not tow a trailer in cruise control. These old trucks may be the source of some thinking you should not tow in cruise control. I tow in cruise control on a regular basis while towing with trucks I have owned since 2008 with no issues. I do not use cruise control when the pavement is wet or slick.

carver 1 · 12-12-2013, 11:53 AM

I am really confused now. I just called Airstream to find out what the difference between the LTX MS/2 P235/75R15XL and the LTX (P) would be for my AS and was told that under no circumstances should i use either of these tires. What's up? They told me that i should only use a tire that is ST. Help!

>>ron<<

m.hony · 12-12-2013, 11:55 AM

I do not use cruise control when the pavement is wet or slick.

True dat! NEVER use cruise on wet pavement! Ask me how I know! When hydroplaning on cruise you have already lost it before you have time to correct- if not on cruise you just pick your foot up off the accelerator! On cruise it just keeps spinning out of control...
I have bad joints- ankles, knees, hips- I have to use cruise control-

dkottum · 12-12-2013, 01:47 PM

Quote:

Originally Posted by carver 1

I am really confused now. I just called Airstream to find out what the difference between the LTX MS/2 P235/75R15XL and the LTX (P) would be for my AS and was told that under no circumstances should i use either of these tires. What's up? They told me that i should only use a tire that is ST. Help!

>>ron<<

Maybe because the load rating of these 15" tires (derated for trailer use) is too low. Airstream offers the 16" Michelin LTX MS/2 as an option, and uses them as standard on Eddie Bauer models.

sb55 · 12-12-2013, 03:06 PM

Quote:

Originally Posted by dkottum

Maybe because the load rating of these 15" tires (derated for trailer use) is too low. Airstream offers the 16" Michelin LTX MS/2 as an option, and uses them as standard on Eddie Bauer models.

What does "derated" mean?

Lance M · 12-12-2013, 03:58 PM

Quote:

Originally Posted by carver 1

I am really confused now. I just called Airstream to find out what the difference between the LTX MS/2 P235/75R15XL and the LTX (P) would be for my AS and was told that under no circumstances should i use either of these tires. What's up? They told me that i should only use a tire that is ST. Help!

>>ron<<

Hi Ron,
There are lots of threads about Airstreamers using the Michelin LTX M/S2 P235/75/15XL on their trailers.
Here are some of the more informative threads.
http://www.airforums.com/forums/f438...ire-71294.html
http://www.airforums.com/forums/f438...5-a-67720.html
http://www.airforums.com/forums/f438...-xl-96185.html
http://www.airforums.com/forums/f438...ade-99125.html

Pay particular attention to posts from Capri Racer, Tireman9 (Tire Engineers) AndyT (Airstream Dealer) and Rich Luhr. Rich is the editor of Airstream Life and has been using the Michelin LTX M/S LT235/75/15 LRC tires on his 30' bunkhouse.
I'm sure Airstream has the "standard answer" for these types of questions, and I believe that is what you got. The standard answer of "you should use ONLY ST tires on a trailer" or "You should ONLY use the type, size and rating that is listed on the MFR's tire load card" are what you typically hear from tire sellers, some trailer dealers and others in the business. This mindset is hard to overcome. It can be debunked by reading the Tire and Rim Manufacturers Association publications. switz has them handy for you to read.

Just like most tire choices, someone will tell you are making a mistake. Whatever choice you make, make it a good one that is based on safety, experience, research and your own best judgement.
Good luck and Happy streamin!

Wazbro · 12-12-2013, 08:19 PM

Quote:

Originally Posted by sb55

What does "derated" mean?

In the case of P rated tires it means that the Tire and Rim Manufacturers Association state that the weight rating for P rated tires is lowered by 10% when used on light trucks or trailers.

switz · 12-13-2013, 08:14 AM

The reason a tire is derated for load capacity is spelled out in the federal regulation:

49 CFR 571.110

Tire selection and rims and motor home/recreation vehicle trailer load carrying capacity information for motor vehicles with a GVWR of 4,536 kilograms (10,000 pounds) or less.

S4.2.2.1
Except as provided in S4.2.2.2, the sum of the maximum load ratings of the tires fitted to an axle shall not be less than the GAWR of the axle system as specified on the vehicle's certification label required by 49 CFR part 567. If the certification label shows more than one GAWR for the axle system, the sum shall be not less than the GAWR corresponding to the size designation of the tires fitted to the axle.

S4.2.2.2
When passenger car tires are installed on an MPV, truck, bus, or trailer, each tire's load rating is reduced by dividing it by 1.10 before determining, under S4.2.2.1, the sum of the maximum load ratings of the tires fitted to an axle.

S4.2.2.3
(a) For vehicles, except trailers with no designated seating positions, equipped with passenger car tires, the vehicle normal load on the tire shall be no greater than 94 percent of the derated load rating at the vehicle manufacturer's recommended cold inflation pressure for that tire.

(b) For vehicles, except trailers with no designated seating positions, equipped with LT tires, the vehicle normal load on the tire shall be no greater than 94 percent of the load rating at the vehicle manufacturer's recommended cold inflation pressure for that tire.

So my Michelin LTX (P) 235/75R15 XL tires that were mounted on our 25FB International Serenity in January 2013 had 2,183 pounds as the load limit on their sidewall. Thus, per the regulation above, the tire was derated to 1,985 pounds load capacity for sizing purposes. They were fitted to the Airstream axles that are rated 3,600 pounds, so two tires were rated 3,970 pounds and exceeded the axle rating per the regulation.

Despite the letters "LTX" in the tire "name" it is NOT a truck tire. The "P" tells the user it is a passenger tire and the "XL" says it has an extra load rating capacity.

For my camping ready 25FB, there was about a 22% safety margin between the actual axles load and the derated capacity of the tires.

For my heavier Classic model 30 trailer (by 2,700 pounds GVW and empty weight exceeding the GVW of the 25FB), I needed a greater load rating tire. So I selected the same tire used by Airstream on their Eddie Bauer models (Michelin LT225/75R16/E LTX M/S2 Michelin part number 05681) and in the hallway for sale at the factory store along with the SenDel T03-66655T wheels. These tires are rated 2,680 pounds and are attached to 5,000 pound rated axles in the three Classic models.

Note that the first two letters are "LT" which stands for light truck and there is no letter "P" in the description. Thus this tire does NOT need to be derated for either truck or trailer use.

Neither Michelin tire has a speed restriction of 65 mph and can be run at all legal speeds posted in the US.

If I installed two of the 15" Michelin tires mentioned above with a combined capacity of 3,970 pounds on 5,000 pound rated axles, I would be in violation of the regulation quoted above and in case of an incident might have some issues for knowingly installing underrated tires on the trailer.

The Chinese made GYM tires are rated 2,540 pounds and are speed limited to 65 mph. I was not pleased reading about their service history and damages caused by frequent failures on this and other RV related forums.

I tend to err on the side of extra capacity and the best tires available for all my vehicles. All of my four wheeled vehicles currently have Michelin tires as have all the others over the last 48 years with no blowouts or other tire failures.

The 2014 Classic model 30 Airstream trailer, when new, is an expensive item to purchase. Spending 1.5% of that cost on high quality tires and wheels to prevent a tire related issue makes sense to me. If I have to ask what it costs to operate a luxury item, I should not be buying that luxury item.

YMMV

m.hony · 12-13-2013, 10:02 AM

I don't understand "derating".
Does a 4,000# car weigh more than a 4,000# truck or trailer?

Lance M · 12-13-2013, 10:14 AM

Quote:

Originally Posted by m.hony

I don't understand "derating".
Does a 4,000# car weigh more than a 4,000# truck or trailer?

From what the tire engineers write, it has to do with different physics and dynamics of cars, trucks and trailers.

switz · 12-13-2013, 10:32 AM

Obviously, the core issue is the tire construction with car sidewalls offering a soft ride and truck walls overing a stiffer ride to carry heavier loads in weight and side loads imposed for example by a large slide in camper with a lot of sail area to catch cross winds and transfer that stress to the tires.