Tire Stiffness & trailer swaying - resolution

In article ,
Tnet says...
In article i68mb.13071$Ec1.1157392@bgtnsc05-
news.ops.worldnet.att.net, says...

Also if you had the budget for it, going with a lower profile tire on a
bigger rim and maintaining the original outside diameter would sounds like
promising solution too.
http://www.tirerack.com/tires/tirete...al/plusone.htm

The most interesting thing to me about Chris's experience is fixing a
trailering problem by changing the tires on the tow vehicle, something
I don't recall hearing about before. Each of the changes he made...

From an article about the Forester in our newspaper:

"On the road, the ride is very good, and handling is exceptionally
nimble though the 16-inch all-season radials moan and and scream when
you take a corner faster than they'd like, which is anythingg over
about 20 MPH. With different tires, the Forester XT would make a great
daily driver."

So, sounds like they went for the 'bottom line' on the tires.
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Eric Greenwell
Richland, WA (USA)

"Eric Greenwell" wrote in message
The most interesting thing to me about Chris's experience is fixing a
trailering problem by changing the tires on the tow vehicle, something
I don't recall hearing about before. Each of the changes he made...

So, sounds like they went for the 'bottom line' on the tires.
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Eric Greenwell
Richland, WA (USA)

Eric.
I think the critical change was the lowering of the hitch point.
I have a Chevy Tahoe with Geolanders on it. I play with sports cars
a bunch and I can't believe how good these tires were at the limit.
When I changed the brakes a bit ago you could clearly see where
I was on the bump stops from cornering. I was suprised to see that much
body roll indicated when the feedback in the seat was so secure.

Besides that, tires usually are reactive to forces, not force generators.
In order for an oscillation to be established, the tires must be excited by
something. A high hitch raises a trailer CG ans contributes mightily to
swaying back and forth. Stiffer tires would be more difficult to excite,
but
they are masking the force, not curing its existance.

Scott Correa

In article , scorrea-removethis-
@socket.net says...
Besides that, tires usually are reactive to forces, not force generators.
In order for an oscillation to be established, the tires must be excited by
something. A high hitch raises a trailer CG

It's hard to see how this can be, since the CG is so close to the
trailer wheels. Raising the hitch 6" would raise the trailer CG less
than 1".

ans contributes mightily to
swaying back and forth.

The explanation that seems more likely to me is the higher hitch lets
the trailer roll the tow vehicle more, which would introduce steering
forces.

Chris also said:

"Other advice that helped included lowering the hitch position and
shortening the hitch to reduce the distance from the ball to the rear
axle."

It sounds like he tested the hitch effect separately from the tire
changes.

Stiffer tires would be more difficult to excite,
but
they are masking the force, not curing its existance.


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Eric Greenwell
Richland, WA (USA)