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Budget M3 · 09-14-2012, 09:58 PM

Hi Gang,

Just bought a completely restored 1960 22' Safari. I haven't weighed it yet, but advertised original weight according to airstreamguy.com was only 2900lbs dry. It was restored by Revitalized Trailers, Inc, and has had the axle replaced with modern parts including electric brakes, but it is still a single axle. I will be towing it with a Porsche Cayenne Turbo which is capable of travelling much faster than I am sure is advisable with the single axle trailer.

I am used to towing an enclosed 18' cargo trailer with a car inside (~5000lb total weight) and can safely tow that combination at 75-80mph all day long with the Cayenne. That setup has dual 3500lb axles, however.

So....looking for recommenations on what folks would consider "too fast" for an old single axle AS. Thoughts?

idroba · 09-14-2012, 10:45 PM

With a new axle, no reason you can't tow at reasonable speeds. Single axle does not matter. I tow my single axle Argosy with a new Dexter at whatever speed feels right. Mostly I tow at 55 to 65 on two lane roads, but have no problem going 75 on Interstates if I feel like it. Normally 70 is my interstate speed though.

Obviously, a tire issue with a single axle can be more of a problem than a dual axle, otherwise there is no reason to worry.

overlander63 · 09-15-2012, 03:31 AM

Speed rating for trailer tires is 65mph, no matter what condition the trailer itself is in.

xrvr · 09-15-2012, 04:39 AM

Yes, tires rated at 65mph. Jim

Bill M. · 09-15-2012, 07:18 AM

Put real tires on it. Blowout on a single axle? How it is loaded and hitched might make a big difference. You probably can determine your comfortable speed better than we can guess. I would think if it exhibits any signs of instability or sway at almost any speed it is not loaded or hitched correctly and is thus unsafe at all speeds. My idea of a safe speed might be different from yours.

Bruce B · 09-15-2012, 07:38 AM

Quote:

Originally Posted by Bill M.

Put real tires on it. Blowout on a single axle? How it is loaded and hitched might make a big difference. You probably can determine your comfortable speed better than we can guess. I would think if it exhibits any signs of instability or sway at almost any speed it is not loaded or hitched correctly and is thus unsafe at all speeds. My idea of a safe speed might be different from yours.

Somewhere on the forum is a post titled "ouch"......(using my iPad or I would post the picture of the accident here now)
just saying.....
Bruce

markdoane · 09-15-2012, 08:39 AM

I believe a dual axle trailer will have a slight advantage over a single axle trailer, all other things being equal.
Trailer stability is the critical speed where the system becomes underdamped. Above the critical speed any disturbance in the system will cause an oscillation that increases until the trailer upsets. Trailer stability depends (in part) on tire sidewall stiffness.
Four tires will usually have more total stiffness than two tires. Therefore a two axle trailer is will have a higher critical speed.
However, if you are stuck with a single axle and two tires, you should get tires with the stiffest sidewall possible. Normally those are the ST tires because they are designed for non-steering axles, where LT tires need to have a more compliant sidewall as they are also used on steer axles. This is a case where you could be worse off with LT tires, even if they are rated for higher speed.

polarlyse · 09-15-2012, 08:58 AM

I just " GO WITH THE FLOW" mostly, up to the speed limit that is. I find 65 or so to be a comfortable speed where it's safe. Out west where we see speed limits approaching 75 I pretty much keep to my 65 zone.

RangerJay · 09-15-2012, 09:11 AM

I can see that the Porsche might be a problem - but if you feel you won't be able to control the impulse to drive faster than you should with the trailer on - then give me a call - for a fellow Airstreamer I'd be happy to swap tow vehicles with you while you are on holidays ......

Jay

Budget M3 · 09-15-2012, 10:43 AM

Quote:

Originally Posted by Bill M.

Put real tires on it. Blowout on a single axle? How it is loaded and hitched might make a big difference. You probably can determine your comfortable speed better than we can guess. I would think if it exhibits any signs of instability or sway at almost any speed it is not loaded or hitched correctly and is thus unsafe at all speeds. My idea of a safe speed might be different from yours.

Good advice on the tires. Since most of my travel will be out west (AZ, NM, CO, ...) I expect I'll be doing a lot of freeway driving, so I'll make sure the tires are up to snuff and have the highest speed rating I can find. Thanks!

Budget M3 · 09-15-2012, 10:48 AM

Quote:

Originally Posted by RangerJay

I can see that the Porsche might be a problem - but if you feel you won't be able to control the impulse to drive faster than you should with the trailer on - then give me a call - for a fellow Airstreamer I'd be happy to swap tow vehicles with you while you are on holidays ......

Jay

Good one, Jay! You successfully detected that I am often unable to control the impulse to drive faster than I should with the P-truck. Hence my question in the first place!

Budget M3 · 09-15-2012, 10:54 AM

Quote:

Originally Posted by markdoane

I believe a dual axle trailer will have a slight advantage over a single axle trailer, all other things being equal.
Trailer stability is the critical speed where the system becomes underdamped. Above the critical speed any disturbance in the system will cause an oscillation that increases until the trailer upsets. Trailer stability depends (in part) on tire sidewall stiffness.
Four tires will usually have more total stiffness than two tires. Therefore a two axle trailer is will have a higher critical speed.
However, if you are stuck with a single axle and two tires, you should get tires with the stiffest sidewall possible. Normally those are the ST tires because they are designed for non-steering axles, where LT tires need to have a more compliant sidewall as they are also used on steer axles. This is a case where you could be worse off with LT tires, even if they are rated for higher speed.

Hmmmm...that's something to think about. When I started my search for a trailer, I was set on getting a dual axle since I wanted something 19-23' and wanted that extra stablity I have gotten used to with my other trailer. When searching for a vintage AS, however, one often has to make compromises, and in this case everything else about the trailer was perfect except that it is single axle so I decided to take the leap.

What sources do you folks use for trailer tires? I know a lot about performance CAR tires, but the trailer stuff is new to me. I think maybe a call to a trailer tire specialist might be helpful at this point...

Budget M3 · 09-15-2012, 11:00 AM

Quote:

Originally Posted by Bruce B

Somewhere on the forum is a post titled "ouch"......(using my iPad or I would post the picture of the accident here now)
just saying.....
Bruce

Yikes! That would certainly ruin one's day. Assuming that was an emergency/avoidance situation, I sure hope my Cayenne will be more stable than the extended cab pickup in the pictures. I realize it's no guarantee, but at least my TV weighs more than my trailer!

http://www.airforums.com/forums/f42/ouch-96402.html

Budget M3 · 09-15-2012, 11:06 AM

Thanks to all who helpfully point out that our trailer tires are rated for only 65mph. I was not aware of that.

Safari-Rick · 09-15-2012, 11:15 AM

Quote:

Originally Posted by overlander63

Speed rating for trailer tires is 65mph, no matter what condition the trailer itself is in.

Ditto !

idroba · 09-15-2012, 11:19 AM

I have had single and dual axle Airstreams over the past 34 years. All have been 25' or under. In all honesty, and with a huge number of towing miles under my belt, I cannot say that one is better than the other. The only real difference is in the case of tire failure. With a single axel, you know it immediately and must do something immediately. With a dual axle setup, you may not even know of tire failure until the tire pieces beat up the side of the trailer and cause much damage. But the trailer may still tow fine....

Last year I changed to 16" wheels and LT ragwall tires on my single axle Argosy. They are rated to 80 psi, for max load. Since my load is way under the max rating I run 60 psi for the softer ride, and easier on the interior (less stiff sidewalls). My Jeep Grand Cherokee and Argosy (Andersen hitch) run as if one unit. The Jeep solo feels like the Jeep with trailer in tow. I usually drive at 55 to 65 on good secondary roads, when on Interstates I drive about 70, but have been over that at times.

So, in my personal case, I have no reservations about single axes, nor do I feel that LT tires with less stiff sidewalls, even de rated ones, are a problem. Every "expert" has a different set of their own criteria, experience, and judgement. I am not sure anyone has the final answer.

Budget M3 · 09-15-2012, 11:33 AM

Quote:

Originally Posted by idroba

I have had single and dual axle Airstreams over the past 34 years. All have been 25' or under. In all honesty, and with a huge number of towing miles under my belt, I cannot say that one is better than the other. The only real difference is in the case of tire failure. With a single axel, you know it immediately and must do something immediately. With a dual axle setup, you may not even know of tire failure until the tire pieces beat up the side of the trailer and cause much damage. But the trailer may still tow fine....

Last year I changed to 16" wheels and LT ragwall tires on my single axle Argosy. They are rated to 80 psi, for max load. Since my load is way under the max rating I run 60 psi for the softer ride, and easier on the interior (less stiff sidewalls). My Jeep Grand Cherokee and Argosy (Andersen hitch) run as if one unit. The Jeep solo feels like the Jeep with trailer in tow. I usually drive at 55 to 65 on good secondary roads, when on Interstates I drive about 70, but have been over that at times.

So, in my personal case, I have no reservations about single axes, nor do I feel that LT tires with less stiff sidewalls, even de rated ones, are a problem. Every "expert" has a different set of their own criteria, experience, and judgement. I am not sure anyone has the final answer.

I thought I might generate some differing opinions on this topic.

All of us have expertise to offer when calling on our own personal experiences. Your thoughtful response is extremely helpful!

I'm still trying to decide whether I want to use a leveling hitch or stabilizing bars, too. The trailer I bought comes with a hitch (no idea which one), but the P-truck has an adjustable air suspension and every electronic control in the book (anti-sway, pitch, yaw, traction, stability, etc.), so not sure I really need the extra hitch control. From what I have read, "expert" opinions on the use of a hitch with the Cayenne/Touareg actually run ~3:1 in favor of no LL or weight distribution hitch.

Budget M3 · 09-15-2012, 11:38 AM

Quote:

Originally Posted by Budget M3

Thanks to all who helpfully point out that our trailer tires are rated for only 65mph. I was not aware of that.

...or maybe not. I just checked tirerack.com for trailer tires and found that Kumho offers a tire that is Q-rated (up to 100mph). Not that I would ever tow a trailer that fast, but it would be nice peace of mind to know that I've got some margin when travelling at 75mph on I-10 through Gila Bend, AZ, in July...

Friday · 09-15-2012, 01:37 PM

You are looking at this from the wrong angle... ie, the speed rating of the tires. Trailers gain momentum exponentially the faster they go, so especially in a single axle, if it starts wagging, it won't matter how many turbos you've got under the hood - you are going for a ride.

With the possibility of tire failure on a single axle, I would invest in a TPMS for it.. then if you are going to test the boundaries of safe towing, at least you'll be informed.

Or, just slow down and enjoy the fact someone else did as well, and got your trailer to be 50+ years old and still operating.

overlander63 · 09-15-2012, 03:19 PM

Quote:

Originally Posted by Friday

You are looking at this from the wrong angle... ie, the speed rating of the tires.

Or, just slow down and enjoy the fact someone else did as well, and got your trailer to be 50+ years old and still operating.

That was the point I was trying to make, but as usual everything went off on a tangent. 65 should be the maximum, not a good jumping off point to go upwards. Stop trying to make the trailer tow faster, that is not the reason for having an RV. If all you want to do is go faster, maybe you should sell the trailer and buy a drag car.
If you put the right speed rated tires on it, you can tow at 99mph. Do I think you should? No.
Many states have a 55 mph speed limit for trailers. That speed limit is, in many cases, to put a stop to people trying to see how fast they can tow their trailers.