I read periodically about UNIDIRECTIONAL tires.
WHY do they exist ???
Sounds to me like Chrysler’s silly experiment with L and R lugnuts back in the
60s. Such a great idea they no longer do it. The wheels didn’t fall off after
they did what most if not all other manufacturers did – make all wheel studs R
hand thread.
Mechanics were always snapping bolts during removal with high powered airguns.
TIA
I suspect it has something to do with the ability to further optimise the
tire’s design by constraining one of the application variables…
But then I’m often accused of having radical perspectives.
"Conase" <con…@aol.commado> wrote in message
news:20030802212624.03115.00001609@mb-m01.aol.com…
- Hide quoted text — Show quoted text -
> I read periodically about UNIDIRECTIONAL tires.
> WHY do they exist ???
> Sounds to me like Chrysler’s silly experiment with L and R lugnuts back in
the
> 60s. Such a great idea they no longer do it. The wheels didn’t fall off
after
> they did what most if not all other manufacturers did – make all wheel
studs R
> hand thread.
> Mechanics were always snapping bolts during removal with high powered
airguns.
> TIA
In article <20030802212624.03115.00001…@mb-m01.aol.com>,
con…@aol.commado (Conase) wrote:
> I read periodically about UNIDIRECTIONAL tires.
> WHY do they exist ???
The best tread patterns for rain use are directional, especially the V
patterns of modern high-performance tires like the Toyo T-1S. If you
mount them backwards, they won’t channel water away from the contact
patch efficiently.
The advantage of such designs is real, even dramatic–my Toyos have as
much grip in the wet as most all-seasons do in the dry.
Asymmetical tread patterns are generally optimized for dry grip, with
large solid blocks at the outer shoulder and most of the rain grooving
toward the inside. The Falken Azenis is a good example: a superb dry
tire that can still be driven in the rain (though with less wet grip
than a directional tire).
Search images.google.com for photos of these tires.
–
Lanny Chambers, St. Louis, USA
’94C
the alignment page:
http://www.hummingbirds.net/alignment.html
Conase wrote:
> I read periodically about UNIDIRECTIONAL tires.
> WHY do they exist ???
Tread patterns may be designed to effectively "pump"
water out of the contact patch area; running this
pattern backwards may result in water being pumped
into the contact patch area.
In article <20030802212624.03115.00001…@mb-m01.aol.com>, con…@aol.commado
says…
>I read periodically about UNIDIRECTIONAL tires.
>WHY do they exist ???
>Sounds to me like Chrysler’s silly experiment with L and R lugnuts back in the
>60s. Such a great idea they no longer do it. The wheels didn’t fall off after
>they did what most if not all other manufacturers did – make all wheel studs R
>hand thread.
>Mechanics were always snapping bolts during removal with high powered airguns.
They can give you better wet weather performance. Not silly at all.
—————–
Alex __O
_-\<,_
(_)/ (_)
Conase wrote:
> I read periodically about UNIDIRECTIONAL tires.
> WHY do they exist ???
> Sounds to me like Chrysler’s silly experiment with L and R lugnuts back in the
> 60s. Such a great idea they no longer do it. The wheels didn’t fall off after
> they did what most if not all other manufacturers did – make all wheel studs R
> hand thread.
> Mechanics were always snapping bolts during removal with high powered airguns.
> TIA
Unidirctional tires (usually have v-shaped grooves running from center
tread to shoulder) tend to increase the evacuation of water from under
the tire. Mounted backwards, they pump water toward the center of the
tread.
IIRC, one of the common car magazines did a tire comparo test a number
of years ago, and tried the reversal on a unidirectional brand. Seems
to me they reports a 3% increase in wet stopping distance with the tires
backward.
Lanny Chambers <la…@hummingbirds.net> wrote:
>In article <20030802212624.03115.00001…@mb-m01.aol.com>,
> con…@aol.commado (Conase) wrote:
>> I read periodically about UNIDIRECTIONAL tires.
>> WHY do they exist ???
>The best tread patterns for rain use are directional, especially the V
>patterns of modern high-performance tires like the Toyo T-1S. If you
>mount them backwards, they won’t channel water away from the contact
>patch efficiently.
>The advantage of such designs is real, even dramatic–my Toyos have as
>much grip in the wet as most all-seasons do in the dry.
That is not quite as I understand it.
I agree that the directional pattern is obviously to push the water out of
the way, matching the directional pattern of inviscid (separated) fluid
flows. But it seems to me that the advantage of your Toyos over all seasons
is that they have a soft rubber compound, not their large-block thread,
whatever its shape.
Tires are said to create grip in three ways:
1) the rubber actually adhering to the road;
2) visco-elastic pressures exerted on the small unevennesses of the road
surface;
3) breaking the rubber from the tire, which is supposedly not very important
for grip (but obviously is for lifetime.)
Water on the road supposedly pretty much kills off the adhesion to the road.
However, high performance tires, being soft, still can get significant grip
from viscoelastic pressures.
Further, it seems to make sense to me that the large tread blocks of high
performance tires are to increase dry performance, with the limit being
slicks. Clearly, with the contact pressure being the same, you would
prefer *small* thread blocks to push the water out of the road/rubber
contact area.
>Asymmetical tread patterns are generally optimized for dry grip, with
>large solid blocks at the outer shoulder and most of the rain grooving
>toward the inside. The Falken Azenis is a good example: a superb dry
>tire that can still be driven in the rain (though with less wet grip
>than a directional tire).
Sounds reasonable to me.
I am currently on Yokohamas AVS ES 100s, after finding another nail in one
of my tires again and being in a hurry to get it fixed. I have not yet
autoxed them, but I can already tell you they have *no* grip in sand at all.
Directional pattern or not. ;)
>Search images.google.com for photos of these tires.
Leon
–
Bozo, the White 96 Sebring Miata .)
Leon van Dommelen
REMOVE THE "z"s -> dommel…@zmiata.net www.dommelen.net
EXIT THE INTERSTATES (Jamie Jensen)
In article <aaduivci4jpqpf8cla9423ge2bo7vkn…@4ax.com>,
dommel…@zmiata.net (Leon van Dommelen) wrote:
> Further, it seems to make sense to me that the large tread blocks of high
> performance tires are to increase dry performance, with the limit being
> slicks. Clearly, with the contact pressure being the same, you would
> prefer *small* thread blocks to push the water out of the road/rubber
> contact area.
The T-1S tread "blocks" are narrow (though very long), and are probably
responsible for its excellent resistance to planing.
> I am currently on Yokohamas AVS ES 100s, after finding another nail in one
> of my tires again and being in a hurry to get it fixed. I have not yet
> autoxed them, but I can already tell you they have *no* grip in sand at all.
Back in my Land Cruiser days, grip in sand was greatly enhanced by
running the L78-15 tires at 10 psi–on a 5000-pound vehicle, this
results in an impressive contact patch, capable of flotation at anything
above a walking speed. My onboard tools included a pump. BTW, at 10 psi,
innertubes are recommended.
–
Lanny Chambers, St. Louis, USA
’94C
the alignment page:
http://www.hummingbirds.net/alignment.html
Lanny Chambers <la…@hummingbirds.net> wrote:
>In article <aaduivci4jpqpf8cla9423ge2bo7vkn…@4ax.com>,
> dommel…@zmiata.net (Leon van Dommelen) wrote:
>> I am currently on Yokohamas AVS ES 100s, after finding another nail in one
>> of my tires again and being in a hurry to get it fixed. I have not yet
>> autoxed them, but I can already tell you they have *no* grip in sand at all.
>Back in my Land Cruiser days, grip in sand was greatly enhanced by
>running the L78-15 tires at 10 psi–on a 5000-pound vehicle, this
>results in an impressive contact patch, capable of flotation at anything
>above a walking speed. My onboard tools included a pump. BTW, at 10 psi,
>innertubes are recommended.
Maybe I should have tried to let out air. Although the tires almost immediately
dug in so deep that the term "contact patch" seemed irrelevant. :)
They seem very good in the wet, BTW. I would think better than the Toyos.
Leon
–
Bozo, the White 96 Sebring Miata .)
Leon van Dommelen
REMOVE THE "z"s -> dommel…@zmiata.net www.dommelen.net
EXIT THE INTERSTATES (Jamie Jensen)