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I am running michelin pro races now and have had a fair bit of mileage on them now. The rear tire is squared off where the tire contacts the road and the "flattened" part is exactly 12mm wide. Is my tire due for replacement??
 

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IMO, at 12 mm, it might be nearing the end. I'd look carefully for any cords that might be starting to show. If you see them, it's definitely dead.
 

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The fact that they are squared is screwing up the handling.
 

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Blue Sugar said:
The fact that they are squared is screwing up the handling.
Complete, utter, and total BS. I defy anyone to be able to detect a meaningful difference in handling when riding squared off tires. The tread and casing is too flexible, and the general tread thickness is to small, for "squaring" of the tread to make a difference.
 

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Agree completely

Mark McM said:
Complete, utter, and total BS. I defy anyone to be able to detect a meaningful difference in handling when riding squared off tires. The tread and casing is too flexible, and the general tread thickness is to small, for "squaring" of the tread to make a difference.
Especially since the squared off tire is on the back. MAYBE you could tell the difference on the front, but it would be hard to sort out the tire shape from all the other wear issues you would have with a high-mileage tire on the front (age hardening, rubber crazing, etc.). Back to the OP's question, while others would replace a tire much sooner, I've never had a problem with waiting until the casing threads start to show - throw out the back tire, move the front to the back, and put a new one on the front.
 

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If that's true, why don't they make tires square to begin with?
 

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Blue Sugar said:
If that's true, why don't they make tires square to begin with?
Do you really need to ask that?

But if you need it spelled out, here it is:

The inner tire casings are always round. The outer "shape" of the tire is determined by the thickness of the tread. Tires become squared off when the tread in the middle wears thinner than the tread at the edges. Because the center of the tread has greater contact with the road, the center wears faster, and tires become squared.

In terms of handling, squared off tires are neither an advantage nor a disadvantage, for the reasons outlined above. But in terms of durability and flat resistance, a squared off tire has less tread where it needs it most (in the middle) and more tread where it needs it least (on the edges).

It makes no practical sense to manufacture a tire with a squared off profile. But it also makes no sense to throw away a tire that has worn into a squared off profile, as long as there is still enough tread thickness left in the center to protect the casing.
 

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I've never seen a round automobile tire, they always have a square profile. Motorcycle and bicycle tires, however, are always round. There's a reason for that, other than "casings are always round", and the reason is that bikes and motorcycles are designed to lean over while cornering, while cars (all being well) do not.

In my experience a squared-off tire does affect handling. When cornering, you have an abrupt transition over the square edge. You definitely feel it, and it definitely interferes with your ability to corner smoothly. When I mount a new tire I immediately notice the difference.

Maybe you guys can't detect it, but I can.
 

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Blue Sugar said:
In my experience a squared-off tire does affect handling. When cornering, you have an abrupt transition over the square edge. You definitely feel it, and it definitely interferes with your ability to corner smoothly. When I mount a new tire I immediately notice the difference.

Maybe you guys can't detect it, but I can.
How would you know the difference between round and squared off tires? All bike tires are squared off (if you look closely enough).
 

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Blue Sugar said:
I've never seen a round automobile tire, they always have a square profile. Motorcycle and bicycle tires, however, are always round. There's a reason for that, other than "casings are always round", and the reason is that bikes and motorcycles are designed to lean over while cornering, while cars (all being well) do not.
It looks like you don't know much about the development of tire technology. In the beginning, all tires, including automobile tires, were round. The only way to "flatten" out the casing profile is with the addition of circumferential belting, constricting the outer diameter of the casing. Since bicycle tires do not have have circumferential belting, their casings are always round.

And no, not all motorcycle tires are round. Some do have shaped casings. Here is an extreme example of this: Mickey Thompson tires


Blue Sugar said:
In my experience a squared-off tire does affect handling. When cornering, you have an abrupt transition over the square edge. You definitely feel it, and it definitely interferes with your ability to corner smoothly. When I mount a new tire I immediately notice the difference.
You are bringing the idea of a "squared tire shape" to an extreme. Tire treads are only a few millimeters thick to begin with, so they can't "square off" to more than a few millimeters of diameter, which is no where near as much as a circumferentially belted tire can be squared off, and also not enough to make a practical difference. The the tread and casing are so flexible, and the pressure against the road so great (100 psi+), the tread easily conforms to the road, regardless of whether some of the center tread has been worn away. Although you may think you can feel a difference, I really doubt that you can.

Blue Sugar said:
Maybe you guys can't detect it, but I can.
See the "What is a poseur" thread under General Discussions.
 

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Blue Sugar said:
I've never seen a round automobile tire, they always have a square profile. Motorcycle and bicycle tires, however, are always round. There's a reason for that, other than "casings are always round", and the reason is that bikes and motorcycles are designed to lean over while cornering, while cars (all being well) do not.

In my experience a squared-off tire does affect handling. When cornering, you have an abrupt transition over the square edge. You definitely feel it, and it definitely interferes with your ability to corner smoothly. When I mount a new tire I immediately notice the difference.

Maybe you guys can't detect it, but I can.

I gotta agree with others that this one sets off the BS detector for me.
 

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Blue Sugar said:
[...] In my experience a squared-off tire does affect handling. [...] When I mount a new tire I immediately notice the difference. Maybe you guys can't detect it, but I can.
It's always possible that this guy is trolling y'all. Assuming that he's being sincere, I would bet that he really does notice a difference in handling when he mounts new tires. After all, sham surgery (placebo) for osteoarthritis of the knee is just as effective as real surgery. SSRIs for depression are only a little more effective than placebo pills. We find that which we seek.
 

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Tread thickenss

Mark McM said:
Tire treads are only a few millimeters thick to begin with
For reference, a Conti GP 3000 tread is about 60 thousandths of an inch, or 1.5 mm. Michelins are thinner than that. Those who can feel the tire shift up on the shoulder are indeed very sensitive :)
 

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You guys might know tires, but you don't know physics.
 

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Thin ice warning!!!!

Blue Sugar said:
You guys might know tires, but you don't know physics.
Now you've REALLY stepped in it! You'd better to be able to back this outrageous statement up with something more than you've brought to the party so far. You're standing on the precipice. My advice would be to step back :)
 

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Kerry Irons said:
Now you've REALLY stepped in it! You'd better to be able to back this outrageous statement up with something more than you've brought to the party so far. You're standing on the precipice. My advice would be to step back :)
wow, you nerds really make me sick. go ride your bikes, talk to some girls and confront your bullies. PLEASE.
 

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Kerry, we don't often reply to the same threads but I just want to mention....

Kerry Irons said:
Now you've REALLY stepped in it! You'd better to be able to back this outrageous statement up with something more than you've brought to the party so far. You're standing on the precipice. My advice would be to step back :)
...that you are THE MAN! :cool:
 

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Kerry is not only encouraging me to confidently squeak out the last few miles on my near treadbare contis, but he also helped me save money on my car insurance by switching to Geico.
 
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