Might a little tire tread actually matter with a large slick?

OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

On Nov 10, 5:11 pm, landotter wrote:
OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

As noted elswhere., the sipes on my City Slickers do hang onto mud and
grass, but in a turn on wet grass, get ready to go splat.

try this one

support a slab of plate glass, get under it, water the top surface (or
thicker liquid?) and have your assistant roll tires thru it
or cut off a peice of used tire tread and press it into the water
watching from below.I haven't done that but have observed water
pooling under materials pressure through glass from below but not to
analyze tread./water only as a passing curiosity not related to
anything.
?
yeah the whole idea is a slit allows pressure relief from the main
pool and this prevents hydroplanning as the HD surface 'hardens' -
water lacking compressive give - while the pool tries to flatten out
and escape the tire's downward pressure. The pool's perimeter doesn't
move outward fast enough especialliy if ura traveling at 140 so you
wind up completely on a fairly frictionless surface. The A/T van tires
I was speaking of cut through 4-5" of thunderstorm interstate poolling
and down the road we roll while the parade stalls out behind
hydroplanning.

On 11/10/2010 7:11 PM, landotter wrote:
OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

One problem with the theory of slicks as always-superior is that it only
presumes totally-clean pavement. Even a tiny bit of sand can lift a
large portion of the slick's "tread" off the ground. With a treaded tire
that slides, some of the sand will roll in-between the tread blocks and
not get back under the tire.

Also an extreme example someone else pointed out, motocoss motorcycles
do not use slicks, as slicks are pretty much useless in mud--where they
essentially hydroplane, even at low "bicycle" speeds.

-------

Another point of contention was in an earlier tire-making post of mine:
board-track racing motorcycles did not use slicks, and neither do
modern-day airplanes.

Board-track racers were raced on board tracks (of course) but used
ribbed tires for that. They DID race in wet weather, yet I have not been
able to find any photos of any race in progress where the motorcycles on
such a track were using anything but ribbed tires. Since slick tires
were easily available at the time, we might presume that there was a
dry-weather benefit to using them.

Pretty much any modern large airplane tire you find is also a ribbed
(circumferential) tread design. The common wisdom explains that this is
to prevent hydroplaning at 200mph+ takeoff and landing speeds, but that
does not make much sense, since at those speeds the traction of the
landing gear is not what controls the airplane's attitude anyway.
........
I did find one instance that indicated that ribbed tire tread is less
likely to suffer chunking at high speeds than other designs do, and this
was the reason that salt-lake racer vehicles tended to use it, but those
speeds are far above what bicycles would (normally) be used at.
~

use a small quantity of water seeing the comparative expansion of area
when different treads are rolled or pressed onto the small pool

On Nov 11, 12:55 am, DougC wrote:
On 11/10/2010 7:11 PM, landotter wrote:

OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

One problem with the theory of slicks as always-superior is that it only
presumes totally-clean pavement. Even a tiny bit of sand can lift a
large portion of the slick's "tread" off the ground. With a treaded tire
that slides, some of the sand will roll in-between the tread blocks and
not get back under the tire.

Also an extreme example someone else pointed out, motocoss motorcycles
do not use slicks, as slicks are pretty much useless in mud--where they
essentially hydroplane, even at low "bicycle" speeds.

-------

Another point of contention was in an earlier tire-making post of mine:
board-track racing motorcycles did not use slicks, and neither do
modern-day airplanes.

Board-track racers were raced on board tracks (of course) but used
ribbed tires for that. They DID race in wet weather, yet I have not been
able to find any photos of any race in progress where the motorcycles on
such a track were using anything but ribbed tires. Since slick tires
were easily available at the time, we might presume that there was a
dry-weather benefit to using them.

Pretty much any modern large airplane tire you find is also a ribbed
(circumferential) tread design. The common wisdom explains that this is
to prevent hydroplaning at 200mph+ takeoff and landing speeds, but that
does not make much sense, since at those speeds the traction of the
landing gear is not what controls the airplane's attitude anyway.
.......
I did find one instance that indicated that ribbed tire tread is less
likely to suffer chunking at high speeds than other designs do, and this
was the reason that salt-lake racer vehicles tended to use it, but those
speeds are far above what bicycles would (normally) be used at.
~

When Kenny Roberts was becoming King of World Championship
(motorcycle) Road Racing. Goodyear was developing road racing tires
for rain with wide diagonal channels - not "V" but straight and
diagonal from sidewall-to-sidewall. The tread in between was
puntuated by notches, too, IIRC.

Very interesting to me was the fact that the same tread pattern
(looked like about the same tires) later became the fastest thing on
dirt-track ovals.

I get spooked regularly by tires slipping in a turn. Sometimes it's
just that, sometimes it turns into a cool sliding turn, sometimes I go
splat (not so often on pavement, but sometimes). From recent years
experience with this on the road bicycle, I think I can say that it's
*never* on clean pavement. Clean, wet paint stripes, yes, but never
clean pavement.

The rains they are coming here now, and it is the most wicked time
(excepting the icy times) traction-wise, with lots of slimy leaves and
tiny sediment everywhere not washed away yet and oil being welled up
out of the pavement. (At this same time the rain severely affects
visibility for cagers, and the darkness she comes, too.)

On Nov 10, 5:11*pm, landotter wrote:
OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

There's a FAQ on this subject:

http://www.sheldonbrown.com/brandt/slicks.html

On Nov 11, 10:41*am, bfd wrote:
On Nov 10, 5:11*pm, landotter wrote:

OK, we're all familiar with the meme of "decorative tread" when it
comes to road tires. That on skinny tires all the tread serves to do
is comfort the ignorant rider and provide a branding visual. Got that,
and with a skinny road tire, it's held up in the real world for me.

A couple weeks ago I took a gentle turn in drizzle by the community
center on the way home and slid out. Gentle meaning that it was a
basic left, and I slowed down far more than I would in the dry.
Perhaps 8mph. Tires were Conti Contact 47s. I run them at around
50psi. They're more or less slicks.

The contact patch on these will be huge compared to, let's say, a 28mm
tire at 90psi. At which point does a larger contact patch for a
cyclist call for a grooved tire, or is it unnecessary for any rounded
tire which pushes water to the side?

There's a FAQ on this subject:

http://www.sheldonbrown.com/brandt/slicks.html

It doesn't address the issue of wide widths and larger contact patches.

On 11/11/2010 11:33 AM, Jobst Brandt wrote:


Grooved tires don't help in the least. If you can't make an impression
on the road, the tread pattern has no effect. If you don't believe
that, then don't fly commercial air, whose tires are slicks that do
enormous braking at 200MPH on wet runways.


Jobst Brandt

Except that big jets don't use slicks:

http://www.google.com/images?q=airli...w=2112&bih=967

~

Jobst Brandt wrote:
:BFD who? wrote:

: OK, we're all familiar with the meme of "decorative tread" when it
: comes to road tires. That on skinny tires all the tread serves to
: do is comfort the ignorant rider and provide a branding visual.
: Got that, and with a skinny road tire, it's held up in the real
: world for me.

: A couple weeks ago I took a gentle turn in drizzle by the community
: center on the way home and slid out. Gentle meaning that it was a
: basic left, and I slowed down far more than I would in the dry.
: Perhaps 8mph. Tires were Continental Contact 47s. I run them at
: around 50psi. They're more or less slicks.

: The contact patch on these will be huge compared to, let's say, a
: 28mm tire at 90psi. At which point does a larger contact patch for
: a cyclist call for a grooved tire, or is it unnecessary for any
: rounded tire which pushes water to the side?

:Grooved tires don't help in the least. If you can't make an impression
n the road, the tread pattern has no effect. If you don't believe
:that, then don't fly commercial air, whose tires are slicks that do
:enormous braking at 200MPH on wet runways.

You live on the same planet as Trevor? Because on Earth, aircraft
tires are grooved. Random pictures of a large commercial jet having a
flat replaced:
http://forums.watchuseek.com/f258/flat-tire-55595.html


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