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Lumatic · 03-01-2013, 04:50 PM

I know a lot of people have switched to 16 inch wheels, but I don't recall a thread on why they are better than 15 inch wheels, so I am starting one.

It's about time to get new tires, so I might as wheel think of changing to 16 inch. I do so like my baby moons on my 15s though.

So here goes...............
WHY?

adonh · 03-01-2013, 05:00 PM

Better LT tire selections with 16" wheels. Higher weight range and speed rating. Safer than the 15 ST tires that are available. I changed to 16" wheels and LT radial ties a few years back. Its just a better combination. Others will provide more detailed data.

afneill · 03-01-2013, 05:03 PM

I think the reasoning is the increased load capacity you get with the 16" Michelin tires. The 235/75R15 Michelins have a load capacity rating of 2183# per tire for a total of 8732 for 4 tires. If that is sufficient to carry with your trailer after derating and allowing for the 20 per cent safety margin then you could stay with 15' tires. If you need more load capacity the 16" Michelins have a capacity of approximately 2650# per tire, or 10,600 for four tires. If you need greater capacity than the 8732 and want to go with the Michelin tires, you will need to go to the 16" tire. That is my understanding and an untechnical explanation.

dsrtgrls · 03-01-2013, 05:11 PM

i finally get it i really get it. thanks all.

Phoenix · 03-02-2013, 12:57 AM

Suggested reading:

http://www.airforums.com/forums/f465...res-69297.html

http://www.airforums.com/forums/f438...oll-76867.html

Note: It may may take some time to wade through the entire threads, but you should get the idea after a couple of pages of each.

Bob Thompson · 03-02-2013, 03:50 PM

The 16" thing pretty much started here: http://www.airforums.com/forums/f438...res-16506.html

What I wrote in May of 2005 is pretty much true thru today.

Phoenix · 03-03-2013, 02:51 AM

Yes, how could I have forgotten...

Over time, this discussion has been (and still is) rehashed a couple of times a year: In the spring before the camping season starts, and in the fall when many Airstreamers are returning home with summer tire-failure horror stories from their travels.

If the Airstream design staff and factory, and those of us who later converted to 16-inch wheels and LT tires, had followed Bob Thompson's initial recommendations in 2005, there would be only a few tire discussion threads, and most of those would be in AirForums' "inactive" history database.

Plus, the huge piles of used tires waiting to be recycled would have significantly fewer carcasses from Airstreams; because LT tires are proving to be more reliable than their ST counterparts. And, they are capable of running more miles before replacement (due to age), than ST tires (due to tread separation and/or blowouts).

So, special thanks to Bob Thompson!

BigAl · 03-03-2013, 06:05 AM

To the original poster.
If you have a light weight trailer you may be able to find 15 inch LT tires that have sufficient load capacity which would save the cost of new wheels.
Al

ROBERT CROSS · 04-21-2013, 04:43 PM

"To the original poster.
If you have a light weight trailer you may be able to find 15 inch LT tires that have sufficient load capacity which would save the cost of new wheels."

My thinks too...

But it is the IN thing to do...

Bob

SteveSueMac · 04-23-2013, 08:03 PM

Quote:

Originally Posted by afneill

I think the reasoning is the increased load capacity you get with the 16" Michelin tires. The 235/75R15 Michelins have a load capacity rating of 2183# per tire for a total of 8732 for 4 tires. If that is sufficient to carry with your trailer after derating and allowing for the 20 per cent safety margin then you could stay with 15' tires. If you need more load capacity the 16" Michelins have a capacity of approximately 2650# per tire, or 10,600 for four tires. If you need greater capacity than the 8732 and want to go with the Michelin tires, you will need to go to the 16" tire. That is my understanding and an untechnical explanation.

Thanks for this info. I feel a bit numb having read most of the LONG discussion on this but this explanation is starting to click for me.

Some thoughts/questions...

The manual for my 2012 FC 27FB (p. D-14) says that a Goodyear ST225/75 R15 tire inflated to 65 PSI has load capacity of 2540 lbs.

The tire placard on my trailer (see photo) says the weight at the factory was 5821 lbs and the GVWR is 7600 lbs (for 1779 lbs cargo capacity).

So even if completely maxed out at 7600 lbs, am I correct in understanding that my 4 GYMs have plenty of load capacity (10,160 lbs) even adding 1520 lbs (20%) to GVWR?

I don't want to "cheap out" - if the 16s are required for this trailer, I'd rather get them - of course, if required, I'm wondering why AS would put the 15s on?? And if the 15s are adequate, I'd rather keep it as stock as possible.

Wide open to thoughts here!

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dkottum · 04-23-2013, 08:26 PM

16" wheels/tires are not required for your trailer, nor ours. But it came equipped with 15" Good Year Marathons, and they do not have a good record of reliability. When they fail they can damage the trailer badly.

We are retired and not getting younger, and do not care to deal with this. I decided to get new Michelins tires as insurance against this, and new 16" wheels in the process because I have see no reports of failures of this combination.

I bought 16" Sendel T02 wheels that look just like the original wheels, and Michelin tires. We travel a lot, usually far from home. It is a great peace of mind not thinking about tire failure on the interstate or in the middle of nowhere, it can happen, but much less likely. That has made it worth the reasonable price of the upgrade.

doug k

ROBERT CROSS · 07-04-2013, 02:08 PM

2003 Classic, still using 15's.

Bob

cwf · 07-04-2013, 02:14 PM

I may upgrade...will see. For now stock

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switz · 07-04-2013, 06:39 PM

Since Airstream installed the 16" Michelin tires with SenDel wheels on the Eddie Baurer model tailers, there is a defacto Airstream approval of this particular tire and wheel combination. Also, this tire and wheel combination is on display at the factory store at Jackson Center as an option one can have installed while having the trailer serviced there.

PharmGeek · 07-04-2013, 07:30 PM

My new 30' bunkhouse will be done by end of october - they use the 15's on it I presume - my dealer is inquiring to airstream about the upgrade - but it I unclear if they will do it per my dealer - he is still asking

Think my GVWR is 8800....

MaxTow · 07-04-2013, 08:14 PM

Many run the 15" Michelin LTX tires on the original rims. Including those with the bunkhouse models (8400 GVWR).

No reports of issues so there is no evidence that I have seen that one must move to 16" wheels to gain peace of mind. This is backed as well by a favourite RV dealer Andy T who likes the 15" Michelins.

The peace of mind is moving away from the ST tires to something built frankly for a more demanding customer - automobile owners. RV owners (in general) seem to be more willing to live with crappy tires.

The fact is that the RV industry is all driven by lowest cost. There's rarely a spectrum of quality choices available. Unlike in the auto world where you can buy a better tire. It does not seem possible with ST tires. They are all dubious.

The other benefit of the 15" Michelins is a softer ride. Max pressure is 50 PSI while the 16" are higher (80?).

PharmGeek · 07-04-2013, 08:19 PM

Sounds better - hope 15 michellins work out for me then

KYAirstream · 08-26-2013, 07:49 PM

Quote:

Originally Posted by afneill

I think the reasoning is the increased load capacity you get with the 16" Michelin tires. The 235/75R15 Michelins have a load capacity rating of 2183# per tire for a total of 8732 for 4 tires. If that is sufficient to carry with your trailer after derating and allowing for the 20 per cent safety margin then you could stay with 15' tires. If you need more load capacity the 16" Michelins have a capacity of approximately 2650# per tire, or 10,600 for four tires. If you need greater capacity than the 8732 and want to go with the Michelin tires, you will need to go to the 16" tire. That is my understanding and an untechnical explanation.

How does one calculate the derating? This may be a dumb question, but is it simply the 20% safety margin or something in addition to it?

SteveSueMac · 08-27-2013, 02:47 AM

Quote:

Originally Posted by KYAirstream

How does one calculate the derating? This may be a dumb question, but is it simply the 20% safety margin or something in addition to it?

I hope I have this right - you might want Capris or Tireman to check in here - but whether using 15s or 16s, I think you start by derating the LT tire by 10% (divide sidewall number by 1.1 - call that LTD1). That's a DOT standard (don't have the link handy but its been posted before). Then - I believe the recommended (but not required) "safety factor" of an additional 15% is taken off the tire's capacity (so divide LTD1 by 1.15 -call that LTD2). If LTD2 x number or tires is equal to or less than your fully loaded, hitched, WD applied trailer weight, you are good to go.

Caveat: That is an uneducated layman's understanding and requires accurate cat scale weights. Consult with a professional before doing something like this.

LFC · 08-27-2013, 05:26 AM

Changing out a set of new Goodyear Marathons is senseless.

Truth is if you had the same number of people using Michelin tires on their trailers and not properly taking care of them you'd be seeing the same if not more complaints on them.

Unlike some I'm not smarter than the tire manufacturers I want a tire that is designed for a trailer....so I will continue to use Goodyears until they come out with a trailer tire that's better.