Siping question

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One thing to note, though, is that if the tire is TOO new, it can actually have poor traction due to the lubricant left over from the molds. I've been finding this out, as my Toyos seem to grip much better now after a month than they did new.
 
Originally Posted by knerml


GM did a study in the early 1970's, that found that snow traction is mostly provided by the number of "edges" the tire presents to the road surface. This led to the development of all season and modern snow tires, with siping. This is also why large aggressive off road tires are typically not effective snow tires.



The old bias ply tires didn't do well with cross-cuts. When radials came out they could finally have "knobby" tread which opened the doors to stuff they'd wanted to do for a while. If you look at a typical bias tire it's pretty much all "highway ribs" albeit with various zig-zags.
 
Originally Posted by Oil_Whisperer
Sipes help for traction on snow.
Tread compound is more important for traction on ice.

Zamboni and other ice resurfacing manufacturers use large, studded bias ply tires. Absolutely zero siping with big tread blocks. While I suppose the studs damage the ice, the machine is going to be forming clean ice behind it.
 
Originally Posted by y_p_w
Originally Posted by Oil_Whisperer
Sipes help for traction on snow.
Tread compound is more important for traction on ice.

Zamboni and other ice resurfacing manufacturers use large, studded bias ply tires. Absolutely zero siping with big tread blocks. While I suppose the studs damage the ice, the machine is going to be forming clean ice behind it.



Lots of heavy equipment uses bias ply still, mostly because they're cheaper, which is a big deal in tires that size. They have a slight advantage in sidewall stability when you're carrying a heavy load up high, too, but other than that radials are just better.

Given as a Zamboni isn't going to be used all that often anyway, it travels slowly and it's going to accumulate very little mileage, the cheaper bias ply is fine.
 
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Originally Posted by y_p_w
Originally Posted by UG_Passat
Originally Posted by supton
Originally Posted by UG_Passat
Ice is only slippery when there is a thin layer of water on it. The sipes enable the tire to break through the water to get the rubber to grip the ice.

Think ice hockey rink and a game. Beginning of period, it is very slippery. By end, the puck moves slower, players move slower, because the thin layer of water and conditioner is gone

I thought ice skates worked by concentrating the force into a small area, and the high force caused the ice to melt. Thus making it slippery for the ice skate to work. Which would argue against siping, makes for high contact force.

I get the point about getting water out of the way though.


Ice skates glide on over a thin layer of water. The Zamboni machine puts a mixture of water and conditioner on the ice surface, as its final step. That is why at the beginning of the period players glide faster and the puck is faster. By the end of the period, the ice "dries" out, as the layer of water that was originally on top, is no longer there, so the ice and skates are now riding on a dry ice surface.

But when you need to turn or propel yourself, that's what have sharp edges of the blade is for. The sharp edges break through the thin layer of water to grip the ice. Worn edges don't break through the layer of water as easily.

The melting of the snow from friction is more relevant to tires, since rubber has a higher coefficient of friction than say steel alloy used on ice skate blades. That higher coefficient of friction enables the ice to transforms it into the thin layer of water.


The theory that skates must glide over a layer of water has supposedly been disproved. It's possible to skate at temperatures so low that ice doesn't melt at all from skates gliding over them.


If you read my other posts, by the end of a period, the puck and skates still glide, but not as well as beginning of the period. If you ice skated before and after a Zamboni machine, you'll see the point.

This also makes the feat of a goalie scoring a goal by himself a spectacular feat, because this ends towards the end of the game, where a team would pull a goalie.
 
I heard that ice resurfacing tires basically never wear out except for the studs. They're also never exposed to UV and ozone unless it's used outdoors a lot.
 
Originally Posted by y_p_w
Originally Posted by edyvw
Originally Posted by Virtus_Probi
Originally Posted by redbone3
I stand corrected. I never thought that the narrow channels in the thread were siping. Siping to me is cutting the thread with a heated blade by some guy at a tire store. Do the tire manufacturers claim their tires are siped? I don't recall any tire ad that mentioned siping.

I copied this from TireRack.com...
"Blizzak DM-V2 tires use Bridgestone's adaptive NanoPro Tech Multicell compound that features a water-loving hydrophilic coating and microscopic bite particles. The Multicell compound remains flexible in below-freezing conditions, wicks water off packed snow and ice while the bite particles deliver more grip and improve braking on glare ice. This compound is molded into a directional tread design featuring 15% more aggressive block edges (than the Blizzak DM-V1 it replaces) where wide lateral and circumferential grooves help channel water, slush and snow away from the contact area for added traction while 3D zigzag sipes increase the number of snow biting edges."
This was actually the first snow tire I looked at.

Sipes also get filled with snow. Snow in sipes provide much better traction and braking when in contact with snow!

Not necessarily the sipes since there's not much area, but definitely the grooves. There are a lot of winter and all-season tire tread designs that are meant to have snow trapped in the grooves since snow sticks to snow. This one has a choppy set of grooves meant to keep snow from falling out.

[Linked Image]


However it's kind of odd. At least in California there's a requirement for "snow tread tires" about the depth of the tread blocks. In order to meet the requirement, an M+S tire needs to have at least 6/32" tread depth to qualify where those alone can substitute for chains. But with true winter tires the tread is going to be filled with snow that stays there, so exactly what's the purpose of requiring tread depth? A good winter tire isn't really using its tread depth to do much since the tread doesn't really bite through the snow.


A good winter tire is only good down to a certain tread depth. For Nokian, the Winter Safety Indicator is worn out when the tread hits somewhere in between 4 and 5mm. Which is .1575" and .19685", around that 6/32" range, then Nokian recommends replacing the winter tires.


Without having Nokian's winter safety indicator, you can tell visually on a winter tire, as the high density siping does not go all the way down the tread block, it only goes down a portion of the tread block. When the high density siping is gone, time for new winter tires.
 
Notice that the high density sipes don't go all the way down.

[Linked Image]Nitto SN-2 by thisistan, on Flickr

There is a reason why for Blizzaks, the ones that use a dual compound, only about 45% of the tread is the Multicell compound, where the tread depth is most effective for snow/ice performance.
 
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Originally Posted by y_p_w
Originally Posted by edyvw
Originally Posted by Virtus_Probi
Originally Posted by redbone3
I stand corrected. I never thought that the narrow channels in the thread were siping. Siping to me is cutting the thread with a heated blade by some guy at a tire store. Do the tire manufacturers claim their tires are siped? I don't recall any tire ad that mentioned siping.

I copied this from TireRack.com...
"Blizzak DM-V2 tires use Bridgestone's adaptive NanoPro Tech Multicell compound that features a water-loving hydrophilic coating and microscopic bite particles. The Multicell compound remains flexible in below-freezing conditions, wicks water off packed snow and ice while the bite particles deliver more grip and improve braking on glare ice. This compound is molded into a directional tread design featuring 15% more aggressive block edges (than the Blizzak DM-V1 it replaces) where wide lateral and circumferential grooves help channel water, slush and snow away from the contact area for added traction while 3D zigzag sipes increase the number of snow biting edges."
This was actually the first snow tire I looked at.

Sipes also get filled with snow. Snow in sipes provide much better traction and braking when in contact with snow!

Not necessarily the sipes since there's not much area, but definitely the grooves. There are a lot of winter and all-season tire tread designs that are meant to have snow trapped in the grooves since snow sticks to snow. This one has a choppy set of grooves meant to keep snow from falling out.

[Linked Image]


However it's kind of odd. At least in California there's a requirement for "snow tread tires" about the depth of the tread blocks. In order to meet the requirement, an M+S tire needs to have at least 6/32" tread depth to qualify where those alone can substitute for chains. But with true winter tires the tread is going to be filled with snow that stays there, so exactly what's the purpose of requiring tread depth? A good winter tire isn't really using its tread depth to do much since the tread doesn't really bite through the snow.

Sipes. I meant specifically those small sipes. They are the one that matters most.
 
So... Siping is for snow traction. Tire compound is more important for ice traction (more pliable in cold temps). Old tires tend to be less pliable, thus old tires will have less ice traction. Correct?
 
Originally Posted by supton
So... Siping is for snow traction. Tire compound is more important for ice traction (more pliable in cold temps). Old tires tend to be less pliable, thus old tires will have less ice traction. Correct?

Compound is for both snow, ice and cold weather regardless is is wet or dry.
Everything is about compound.
 
Originally Posted by supton
.... old tires will have less ice traction. Correct?


YES

https://www.vti.se/en/Publications/...now-grip-for-worn-and-new-winter-_878116

Quote
From the Swedish National Road and Transport Research Institute (VTI):

...This study has measured ice and snow grip for used and new winter tyres, with the purpose to investigate how the road grip on ice and snow for different types of winter tyres degrade by age and degree of wear. In total, 77 tyres have been tested, of which 27 were completely new while 50 were used. The tyres have been tested on smooth ice and packed snow. The results show that with respect to ice grip, the studded tyres have a larger performance decrease when worn, than the unstudded winter tyres. However, the ice grip of worn studded tyres were still clearly superior to that of worn unstudded tyres. The used unstudded tyres of European type have in general a very poor ice grip, on level with two summer tyres that were also tested... The study also shows that the premium tyres in general have better ice and snow performance compared to the budget tyres, for both new and used tyres....
 
Originally Posted by supton
So... Siping is for snow traction. Tire compound is more important for ice traction (more pliable in cold temps). Old tires tend to be less pliable, thus old tires will have less ice traction. Correct?

All tires start losing traction when they're older. Some of the speculation over the Porsche Carrera GT crash that killed Paul Walker was that the tires were 9 years old and had lost much of their grip.

Still - I remember when I was back riding bikes, I was told that typical Michelin or Vittoria folding tires needed to "cure" for at least 6 months for one reason or another. I didn't necessarily understand what the rationale was for doing it.
 
Originally Posted by y_p_w
Originally Posted by supton
So... Siping is for snow traction. Tire compound is more important for ice traction (more pliable in cold temps). Old tires tend to be less pliable, thus old tires will have less ice traction. Correct?

All tires start losing traction when they're older. Some of the speculation over the Porsche Carrera GT crash that killed Paul Walker was that the tires were 9 years old and had lost much of their grip.

Still - I remember when I was back riding bikes, I was told that typical Michelin or Vittoria folding tires needed to "cure" for at least 6 months for one reason or another. I didn't necessarily understand what the rationale was for doing it.

I wonder if those tires had to "cure" by letting anything evaporate off? Mold release or whatever.

Well, the tires I have on my car are about a year old--I installed sometime last winter. I don't recall the date code but they are at worst case 2 years old--but only 1 year in service. I'm around 3-4/32's of tread left, end of life as far as I'm concerned. As expected, traction is suffering (which is fun for handbrake turns, not so much the rest of the time). As such I don't think the rubber has "dried" out much, but who knows.
 
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