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      01-20-2012, 04:23 PM   #1
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PS2 Question for Smart tire people.

So I was looking at my tires on the car and thought all of a sudden that I was somehow sold two right, or two left tires...

I know this sounds weird already, because the next thing I thought to myself is that I KNOW that there is no left or right with PS2's, just an outside and inside.

So Im thinking to myself. How is it possible that one of the best tires out there has tread that goes in opposite directions on the same axle. wouldn't this cause tread wear issues, handling issues, traction issues and who knows what else.

Take a look at the picture before and pretend your looking at them on the back of a car. To me the tread seems to be totally opposite. Like one tire would have better traction than the other.



Am I the only one that is noticing this now after years of running these tires? Can someone try to explain how "physically" this works ok? To me its like if the direction of the holes on our break rotors when opposite ways from right to left. Wouldent that cause different performance?

Embarrassed,
D
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      01-20-2012, 08:36 PM   #2
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Wow, I thought for sure I would get some immediate responses or flamings. Lol but not crickets.

D
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      01-20-2012, 08:51 PM   #3
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Okay, I'll bite...

This is normal, even though it looks strange. The PS2s are asymmetric (there is a different tread compound and pattern inboard vs. outboard) but not directional (it does not matter which direction the tire travels). So all PS2s are the same--there is no specific left-side tire vs. right-side tire--so the outer pattern runs opposite on one side vs. the other (as does the inner pattern). As to why this does not create an issue, I have no idea--I'd like to hear a good explanation, too.

I first noticed this a few years ago with the PS2s on my former car. I immediately began checking out every sports car I could find to see if this was the case with their PS2s, too. I thought maybe I had incorrect tires on one side! Up until that point, I had only been familiar with symmetric, directional tires like the original Pilot Sport and the Bridgestone S03 Pole Positions. With those tires, there is no inboard vs. outboard, but there is certainly a correct direction of rotation!

Once you've noticed this, though, you'll see it everywhere. This asymmetric, non-directional pattern is also used on the OEM PZeros that came on my M3, and on the new Michelin Pilot Super Sports. In fact, I think that asymmetric, directional tires are pretty rare, since, if used in a staggered setup, there is literally a specific LF tire, a specific RF tire, a specific LR tire, etc. It makes for a very careful phone call when you need to replace one tire: "I need a 275/30-19 LEFT-sided tire..."

So it does seem weird that the tread pattern runs in different directions on one side of the car relative to the other with the PS2, PSS, PZero, etc., but I assume the engineers know what they're doing.
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      01-20-2012, 10:27 PM   #4
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Quote:
Originally Posted by paradocs98
Okay, I'll bite...

This is normal, even though it looks strange. The PS2s are asymmetric (there is a different tread compound and pattern inboard vs. outboard) but not directional (it does not matter which direction the tire travels). So all PS2s are the same--there is no specific left-side tire vs. right-side tire--so the outer pattern runs opposite on one side vs. the other (as does the inner pattern). As to why this does not create an issue, I have no idea--I'd like to hear a good explanation, too.

I first noticed this a few years ago with the PS2s on my former car. I immediately began checking out every sports car I could find to see if this was the case with their PS2s, too. I thought maybe I had incorrect tires on one side! Up until that point, I had only been familiar with symmetric, directional tires like the original Pilot Sport and the Bridgestone S03 Pole Positions. With those tires, there is no inboard vs. outboard, but there is certainly a correct direction of rotation!

Once you've noticed this, though, you'll see it everywhere. This asymmetric, non-directional pattern is also used on the OEM PZeros that came on my M3, and on the new Michelin Pilot Super Sports. In fact, I think that asymmetric, directional tires are pretty rare, since, if used in a staggered setup, there is literally a specific LF tire, a specific RF tire, a specific LR tire, etc. It makes for a very careful phone call when you need to replace one tire: "I need a 275/30-19 LEFT-sided tire..."

So it does seem weird that the tread pattern runs in different directions on one side of the car relative to the other with the PS2, PSS, PZero, etc., but I assume the engineers know what they're doing.
Disappointed, no smart ass comment .

OP, I did the same thing...no worries
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      01-20-2012, 10:51 PM   #5
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you tires are going the wrong way!
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      01-23-2012, 02:56 PM   #6
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Paradocs had great info. I'll add a couple notes. I am NOT a tire engineer. I sell a lot of tires, I test a lot of tires, I think about tires pretty much all day, but don't expect lots of calculations and formulas.


When a tire is running 'backwards', the main concern is water evacuation, and in this case water evacuation is straight through the tread via the main circumfrential grooves.

First and foremost, don't get bogged down in the minutia: the PS2 is basically a straight-rib tread design. It consists of circumferential grooves of varying width spaced across the tread of the tire. The ribs between the grooves are basically solid. Water evacuation, the main area of concern if a tire was running 'backwards', is straight through the tread via the main circumfrential grooves.

There are minor diagonal elements in the tire, but they are not as deep or wide as the circumfrential elements. The bigger diagonal grooves are on the shoulders, and they are very close to horizontal, making them equally effective going one way as the other. Some of the elements may do better than others in one direction or the other, but the net effect is equivalent performance going either way.

This is especially happy news for those who like to drive really fast in reverse.
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      01-24-2012, 10:24 AM   #7
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Quote:
Originally Posted by ben@tirerack View Post
This is especially happy news for those who like to drive really fast in reverse.
Good one!

TowMater, ya hear that? Ben's got new shoes for you!!
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      01-24-2012, 11:40 AM   #8
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Haha, Thanks for the responses guys.
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