trailer sway mitigation TSM

At 07:35 18 December 2019, krasw wrote:
I have a newish VW Golf that has trailer-assist option. It has
electronic
stability system for trailer towing, including fancy servo steering that
points the trailer directly to direction you want when reversing.

All I can say is that it goes like a train on rails and I have never had
slightest indication of swaying.


Have a look at these clips.

https://www.youtube.com/watch?v=w9Dgxe584Ss

https://www.youtube.com/watch?v=6mW_gzdh6to

BG wrote on 12/17/2019 9:54 PM:
On Monday, December 16, 2019 at 12:03:02 PM UTC-8, princiar wrote:
Anyone has experience towing a trailer with a car with the trailer sway
mitigation installed?

I used to tow a DG 800 with a single axle trailer with a 4 Runner and found it
got to be quite a adventure. Any rapid turning would end up with a sway side
to side. I now tow with a Range Rover with 20" wheels with low profile tires.
The difference is night and day. IT was easy to understand the the major
difference is the tires. The 4 Runner had a high profile tire that flexed if
you pushed side to side on the rear of the car. The low profile tires have
virtually no sidewall flex. The suspension in the 4 runner was solid with
great sway bars, they however could not over come the flexing in the tire
sidewalls. In the Rover I can easily go any speed I desire with zero sway and
can change lanes at will. Push your car sideways at the rear and observe what
you see. Any motion will reveal why you have sway. I have seen many work
arounds with friction tuning to dampen sway, but none work better than
addressing the root cause.

The tire stiffness that is important is the lateral tread stiffness - how much the
tread deflects under side load. For this reason, radial tires are better than bias
ply tires, even though the bias ply tire might feel "stiffer" in your hand push
test. There are things that tend to increase tread stiffness and "side push
stiffness" at the same time, such as lower profile tires or higher pressure, so
it's easy to mistake what causes the improvement, and what is by-product of the
change.

There are likely other differences between the 4 Runner and Range Rover that make
one tow better than others, such as wheel base and hitch to rear axle distance. IT
would be fun to do the stability test with the same profile tire on vehicle. I
know at least one pilot that improved the stability of his towing by putting low
profile tires on the glider trailer, which is cheap and easy - worth trying if the
other factors (tongue weight, tire pressure, etc) don't help enough.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Monday, December 16, 2019 at 3:03:02 PM UTC-5, princiar wrote:
Anyone has experience towing a trailer with a car with the trailer sway mitigation installed?

An important factor is the tire slip angle; ratio of side to vertical load.
Radial tires have a low slip angle, which is what you need on the trailer
and rear tires plus stiffening the side walls with increased pressure.
Dropping the front pressure also helps.

Something to check; PIK factory trailers had a tip angle adjustment,
a large turnbuckle at the hitch. If this is not tightened down hard,
the side cheek flex allows an extra degree of freedom in the control loop.
The result is dramatically bad as I found out when I neglected this.

Weight at the trailer back is bad, as has been said. Many of us us
are in the habit of stuffing odd items into the rear end; bad idea.

Something to test; a rudder on the tail box controlled by a mechanism
driven by the car/trailer error angle. ( in the right sense of course)
Cables or fly-by-wire ?

John Firth

john firth wrote on 12/18/2019 8:09 AM:
Something to test; a rudder on the tail box controlled by a mechanism
driven by the car/trailer error angle. ( in the right sense of course)
Cables or fly-by-wire ?

Hmm, we could call it a "yaw damper". Mechanical units exist, like the optional
Cobra trailer hitch that clamps onto the ball, so the friction can dampen the
trailer's swaying. Works well, I'm told, and a relatively easy fix, but you must
use a ball that is truly fixed on the hitch, not just bolted on. Follow the
instructions.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Tuesday, December 17, 2019 at 2:01:56 PM UTC-5, Eric Greenwell wrote:
Boise Pilot wrote on 12/17/2019 10:19 AM:
On Tuesday, December 17, 2019 at 10:15:29 AM UTC-7, Jonathan St. Cloud wrote:
On Tuesday, December 17, 2019 at 8:06:29 AM UTC-8, Matt Herron Jr. wrote:
On Monday, December 16, 2019 at 4:43:23 PM UTC-8, JS wrote:
Good shocks seemed to have the biggest effect in my experience.
I have used three different model year Jeep Grand Cherokees as tow cars for
over 35 years. Nelson Funston (JN) is a tire and trailer expert with big heavy
trailers. With my first Jeep, told me to do three things in following order:
-Move some weight forward,-stiffer sidewall trailer tires at max pressure,
-vehicle tires at max pressure. Ancillary advice, maintain Jeep shocks... We
have some interstate speeds of 80 mph in Idaho. No sway!! All my Jeeps were
the 8cyl model so heavier than the old 4cyl and most currently available 6cly
on the road. Also all had 4 wheel drive and the off road accessory that has
different suspension and road clearance. Boise Pilot




Look out when moving trailer weight forward... Never exceed the maximum
tongue weight! Jim

Also tighten up the hitch in the receiver with one of these: they take out
the slop that can add to sway, and quiet down the rig

I found once I stopped towing with a Jeep Grand Cherokee I had no more sway
problems.

Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...load-the-guide

Interesting paper, thanks for the link.

But I'm puzzled by Funston's remark at bottom of p34 that "Bias ply tires generally have 25 % io 30% lower lateral stiffness than radials and are not recommended for use on glider trailers".

Almost every other article I've seen on the web about trailer tires recommends the opposite: i.e. bias ply trailer tires (marked "D" on the sidewall) have stiffer sidewalls and cut down trailer sway.

What are others' opinions on bias vs radial trailer tires?

Ian "IN"

India November wrote on 12/20/2019 7:53 PM:
On Tuesday, December 17, 2019 at 2:01:56 PM UTC-5, Eric Greenwell wrote:

Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...load-the-guide

Interesting paper, thanks for the link.

But I'm puzzled by Funston's remark at bottom of p34 that "Bias ply tires generally have 25 % io 30% lower lateral stiffness than radials and are not recommended for use on glider trailers".

Almost every other article I've seen on the web about trailer tires recommends the opposite: i.e. bias ply trailer tires (marked "D" on the sidewall) have stiffer sidewalls and cut down trailer sway.

What are others' opinions on bias vs radial trailer tires?

These claims are made by people that do not realize it is the tread stiffness
(resistance to lateral deflection) is the important factor in a tire's behavior.
The stiffer the tread, the smaller the slip angle, and small slip angles improve
vehicle stability.

https://suspensionsecrets.co.uk/tyre-slip-angle/

This is not opinion, but engineering fact. Instead of seeking opinions, I suggest
you look for facts; for example, look at tire company websites, tire
recommendations for things like travel trailers, or even wander about a RV trailer
lot, and note the radial tires on all the trailers. The only good feature of a
bias ply trailer tire is the lower price.

As a side note, bias ply trailer tires don't necessarily have the "stiffest"
sidewall (as measured by the "push" method). A few years ago, I measured that
stiffness on three similar sized tires, with the same load rating, for a glider
trailer. The stiffest was an LT (light truck tire), 2nd stiffest was the ST radial
tire, and least stiff was the ST bias ply tire. The LT tire was the most stable,
the ST bias ply tire was the least stable. I can send you a copy of the test
results if you want it.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Note that Nelson Funston's Trailer Dynamics paper was written in 1987. I would bet that tire technology has changed somewhat in the intervening 32 years. Still, the paper is interesting and informative.

wrote on 12/21/2019 6:39 AM:
Note that Nelson Funston's Trailer Dynamics paper was written in 1987. I would bet that tire technology has changed somewhat in the intervening 32 years. Still, the paper is interesting and informative.

The steel belted radial was well-established in 1987. I've discussed tires,
particularly trailer tires, with Nelson many times since then, including recently
about the specific tires to get for my trailer. He has never mentioned any changes
to tire technology that would affect us, nor have I heard of anything.

Also, there is nothing in his paper that depends directly on tire technology. It's
the lateral stiffness of the tire tread that is important; then and now, radial
tires have significantly more stiffness that a comparable bias ply tire.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

On Friday, December 20, 2019 at 11:56:12 PM UTC-5, Eric Greenwell wrote:
India November wrote on 12/20/2019 7:53 PM:
On Tuesday, December 17, 2019 at 2:01:56 PM UTC-5, Eric Greenwell wrote:

Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...load-the-guide

Interesting paper, thanks for the link.

But I'm puzzled by Funston's remark at bottom of p34 that "Bias ply tires generally have 25 % io 30% lower lateral stiffness than radials and are not recommended for use on glider trailers".

Almost every other article I've seen on the web about trailer tires recommends the opposite: i.e. bias ply trailer tires (marked "D" on the sidewall) have stiffer sidewalls and cut down trailer sway.

What are others' opinions on bias vs radial trailer tires?

These claims are made by people that do not realize it is the tread stiffness
(resistance to lateral deflection) is the important factor in a tire's behavior.
The stiffer the tread, the smaller the slip angle, and small slip angles improve
vehicle stability.

https://suspensionsecrets.co.uk/tyre-slip-angle/

This is not opinion, but engineering fact. Instead of seeking opinions, I suggest
you look for facts; for example, look at tire company websites, tire
recommendations for things like travel trailers, or even wander about a RV trailer
lot, and note the radial tires on all the trailers. The only good feature of a
bias ply trailer tire is the lower price.

As a side note, bias ply trailer tires don't necessarily have the "stiffest"
sidewall (as measured by the "push" method). A few years ago, I measured that
stiffness on three similar sized tires, with the same load rating, for a glider
trailer. The stiffest was an LT (light truck tire), 2nd stiffest was the ST radial
tire, and least stiff was the ST bias ply tire. The LT tire was the most stable,
the ST bias ply tire was the least stable. I can send you a copy of the test
results if you want it.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Hi Eric,

Thanks for your reply. I hear you and accept what you say.

Many sources out there on the www (wild, wild web) with advice on trailer towing say that bias-ply tires have stiffer sidewalls and reduce trailer sway--just one example being https://www.westmarine.com/WestAdvis...er-Tire-Basics. Not arguing, just sayin'.

I am be interested in reading your test results. Please email at iandotgrant12atgmaildotcom

Many thanks!
IN

On Friday, December 20, 2019 at 11:56:12 PM UTC-5, Eric Greenwell wrote:
India November wrote on 12/20/2019 7:53 PM:
On Tuesday, December 17, 2019 at 2:01:56 PM UTC-5, Eric Greenwell wrote:

Anyone that wants to hear more from Nelson Funston can download his OSTIV paper on
trailer stability he

http://journals.sfu.ca/ts/index.php/...wnload/779/737

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...load-the-guide

Interesting paper, thanks for the link.

But I'm puzzled by Funston's remark at bottom of p34 that "Bias ply tires generally have 25 % io 30% lower lateral stiffness than radials and are not recommended for use on glider trailers".

Almost every other article I've seen on the web about trailer tires recommends the opposite: i.e. bias ply trailer tires (marked "D" on the sidewall) have stiffer sidewalls and cut down trailer sway.

What are others' opinions on bias vs radial trailer tires?

These claims are made by people that do not realize it is the tread stiffness
(resistance to lateral deflection) is the important factor in a tire's behavior.
The stiffer the tread, the smaller the slip angle, and small slip angles improve
vehicle stability.

https://suspensionsecrets.co.uk/tyre-slip-angle/

This is not opinion, but engineering fact. Instead of seeking opinions, I suggest
you look for facts; for example, look at tire company websites, tire
recommendations for things like travel trailers, or even wander about a RV trailer
lot, and note the radial tires on all the trailers. The only good feature of a
bias ply trailer tire is the lower price.

As a side note, bias ply trailer tires don't necessarily have the "stiffest"
sidewall (as measured by the "push" method). A few years ago, I measured that
stiffness on three similar sized tires, with the same load rating, for a glider
trailer. The stiffest was an LT (light truck tire), 2nd stiffest was the ST radial
tire, and least stiff was the ST bias ply tire. The LT tire was the most stable,
the ST bias ply tire was the least stable. I can send you a copy of the test
results if you want it.


--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Hi Eric,

Thanks for your reply. I hear you and accept what you say.

Many sources out there on the www (wild, wild web) with advice on trailer towing say that bias-ply tires have stiffer sidewalls and reduce trailer sway--just one example being https://www.westmarine.com/WestAdvis...er-Tire-Basics. Not arguing, just sayin'.

I am interested in reading your test results. Please email me at iandotgrant12atgmaildotcom

Many thanks!
IN