OK this may be a really silly thing to ask but I'm curious. Why do the treads on my front and rear tires appear to be opposite. I just installed Michelin Pilot Road 2 tires and they are installed correctly. The "v" for lack of a better name, in the tread, points forward on the rear tire but backwards on the front. What gives? Tire tread on cars all point in the same direction.
I don't doubt Michelin's expertise. My tires are installed with the directional arrows in the correct direction. My understanding is that the grooves are to channel water away. Why then does the front tire have the pattern "reversed?" It seems like it'd be channeling water inward rather than outward.
Looks are deceiving! I couldn't tell you the why of it, just that your tire is on correctly. Michelin pays their engineering staff pretty well for what they do, and I really like the PR2's, so I don't question it..
Get out and RIDE!
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__________________
Well, fire the engines! Spur this iron space-pony on!
Come on people, the reason is obvious: The pattern is designed to ensure that the well-discussed and infamous Michelin front tire cupping/scalloping occurs! This way they sell more front tires to the anal types who replace the tire before the wear bar because they let the irregular wear eat away at them.
I love my PR2's, but the cupping is dissapointing. I would still buy them again though.
I remember being confounded by this question myself. I looked around the net and saw lots of confusion and a few theories. I remember someone saying water evacuation and heavy braking, some others beleived in water evacuation efficiency while turning. And I forgot what else. Reduce water spray to your feet? I've pointed this out on a few friends' rides and they were'nt sure or didn't even realize it. The weird thing is I still have my stock bridgestone bt-56? and the front tread "v" pattern mimics the direction the rear one goes...and its mounted on correctly. What gives?
Come on people, the reason is obvious: The pattern is designed to ensure that the well-discussed and infamous Michelin front tire cupping/scalloping occurs! This way they sell more front tires to the anal types who replace the tire before the wear bar because they let the irregular wear eat away at them.
I love my PR2's, but the cupping is dissapointing. I would still buy them again though.
Use slicks there are no sipes to get tucked down and wear rubber of off during braking so therefore no cupping
Come on people, the reason is obvious: The pattern is designed to ensure that the well-discussed and infamous Michelin front tire cupping/scalloping occurs! This way they sell more front tires to the anal types who replace the tire before the wear bar because they let the irregular wear eat away at them.
I love my PR2's, but the cupping is dissapointing. I would still buy them again though.
fyi any tire is going to cup that has some sort of tread in it, just comes with the territory. My roads and power 2ct's cup alot less than the old shitty shinko's i had on my bike when i got it.
Pluss tires dont go bald, they just turn into street slicks! :-P I kid i kid.
Ah ha, perhaps my joking has lead to a possible theory about tread channel direction. Perhaps this orientation has less to do about water evacuation than it does about minimizing cupping?
The rear tire needs to shed water mostly when it is accelerating (i.e., speed of rotation is increasing, if we define the direction of rotation for forward motion as positive). For a water droplet in the middle of the tire tread, it will feel the tire accelerating in the forward direction, so the water droplet is 'left behind', and the channels are aimed toward the back of the tire (the direction opposite rotation). On the front tire, the most important time to shed water is under braking - when the tire is being accelerated in the opposite direction. As the tire accelerates backwards (i.e., it goes from 2000 rpm to 1000 rpm - this is the same as accelerating the bike backwards, although we often call this 'deceleration'), a water droplet on the tire wants to continue rotating forward, so the grooves are aimed in the 'forward' direction so that the water will flow out of the groove. From a physics point of view, slowing down a bike with the front tire is equivalent to accelerating it backwards, with the front wheel as the drive wheel. It makes sense that the tires would have grooves in opposite directions - one tire primarily accelerates the bike in the forward direction, the other tire only accelerates the bike in the backwards direction (also known as braking).
Boy that sounds believable. Why then, do the 919 stock tires (BT056,) front and rear, and possibly others brands, have the V pointed in the same direction.
Boy that sounds believable. Why then, do the 919 stock tires (BT056,) front and rear, and possibly others brands, have the V pointed in the same direction.
Maybe they are doing it wrong LOL
Here is what I can tell you for certain.
1. Michelin makes the best wet weather tires you can buy. Their full race wets are the best I have ever used a I use Pilot Power street tires as Intermediate Rain tires on the track
2. Bridgestone front tires are the absolute worst tires I have ever used when it comes to cupping & tracking (wandering the grooves of the road).
They go backwards due to the forces invovled when accelerating the bike. To minimize tire wear and maximize stability the groove needs to be parallel to the forces on the tire. That is why the center groove basically runs around the circuference of the tire.
Either on the gas or brake if our straight up the forces run straight. The further you lean over the more the forces on the tread are moving from longitudinal to lateral. So at full lean the gooves are always close to or compeletely radial to the tire.
Between straight up and down, and full lean is what depictss the direction on the "V" the OP is referingg too.
As for water sheding. The tire is not flat. Its round cross section allows it to shed water without the tread. Tread helps of coarse but the direction of the tread for rubber stability is more improtant than for sheding water.
Car tires are flat, so they need the V groove to push water from the center of the tire out the sides. The bike tires round cross section of the bike tire does the same thing on its own.
They go backwards due to the forces invovled when accelerating the bike. To minimize tire wear and maximize stability the groove needs to be parallel to the forces on the tire. That is why the center groove basically runs around the circuference of the tire.
No center groove on PR2s. The rest of your explanation is less than convincing too - no offense.
Yea I know, alot of tires don'thave center grooves anymore. Especially sportier tires. My explination would make more sence with diagrams. If I get motivated this weekend I'll break out a pencil and paper.
It is for tread stability. If the forces are 90 degrees to the grooves the the tread "blocks" deform. The edge bends over. This can be felt in extreme cercumstances. Such as riding dirt bike tires on the street (note these block treads are weak in any directiction since they are square). And it is a big portion of why tires with a "forward" V on the front tire cup so badly.
I got a response from Michelin. You guys talking about acceleration and braking have it right, although they didn't answer the question of channeling water one way vs. the other.
November 09, 2011
Hello mambomonster,
Thank you for your email. We welcome the opportunity to serve you.
The tread pattern of front and rear motorcycle tires are different because the performance function of front and rear tires are not the same. Front tires are designed to provide maximum braking grip and the rear tires are designed to provide maximum grip under accelerating conditions. In order to achieve these performance criteria the tread design of front and rear tires will go in opposite directions.
We appreciate your business and thank you for choosing Michelin.
It is our goal to ensure that your issue has been resolved or your question answered to your satisfaction. If we can assist you further, please respond to this email or call us at 1-800-642-4354 (toll free) between 8:00AM and 8:00PM Eastern Time Monday through Friday or between 8:30AM and 4:30PM Eastern Time on Saturday.
Sincerely,
Ken
Consumer Care Department
Certified Michelin Product Expert
I got a response from Michelin. You guys talking about acceleration and braking have it right, although they didn't answer the question of channeling water one way vs. the other.
November 09, 2011
Hello mambomonster,
Thank you for your email. We welcome the opportunity to serve you.
The tread pattern of front and rear motorcycle tires are different because the performance function of front and rear tires are not the same. Front tires are designed to provide maximum braking grip and the rear tires are designed to provide maximum grip under accelerating conditions. In order to achieve these performance criteria the tread design of front and rear tires will go in opposite directions.
We appreciate your business and thank you for choosing Michelin.
It is our goal to ensure that your issue has been resolved or your question answered to your satisfaction. If we can assist you further, please respond to this email or call us at 1-800-642-4354 (toll free) between 8:00AM and 8:00PM Eastern Time Monday through Friday or between 8:30AM and 4:30PM Eastern Time on Saturday.
Sincerely,
Ken
Consumer Care Department
Certified Michelin Product Expert
GOD [Ken - Certified Michelin Product Expert] Hath spoken..... /debate
Really he just stated what we already knew. Front tire accelrates in the oposite direction therefore it has the tread pattern oposite the rear's. The Michilen man didn't state truely WHY the designs are the way they are.
I stand by my tread stability statement (even if I did state it in a confusing mannor). Minimal tread deflection gives minimal wear, even wear, and good feel.
Really he just stated what we already knew. Front tire accelrates in the oposite direction therefore it has the tread pattern oposite the rear's. The Michilen man didn't state truely WHY the designs are the way they are.
I stand by my tread stability statement (even if I did state it in a confusing mannor). Minimal tread deflection gives minimal wear, even wear, and good feel.
exactly... and this is because the front and rear tires need maximum traction in opposite directions.
I still don't have a good understanding of the traction issue. The grooves are to channel water away. Slicks are for the dry. How does the explanation of front vs. rear "traction" apply to slicks? I want to know why the water grooves are in opposing directions on my PR2 tires. You guys don't know and I think the Michelin man doesn't answer because it likely gets into proprietary technology/design.
I still don't have a good understanding of the traction issue. The grooves are to channel water away. Slicks are for the dry. How does the explanation of front vs. rear "traction" apply to slicks? I want to know why the water grooves are in opposing directions on my PR2 tires. You guys don't know and I think the Michelin man doesn't answer because it likely gets into proprietary technology/design.
Haha, no offense is intended to anyone. I just wish people would admit when they are not sure but have a good guess. Some of the guesses on this seem very reasonable and close to the mark but do not completely explain the question at hand, at least not for me.
I don't really see what so difficult about the explanation. I would suspect that it's pretty obvious engineering design for those in the engineering field. I will try to explain it differently, based on my lay persons understanding of it.
Cutting grooves into the tire introduces new flex dynamics into the tread. Clearly, there would be some flex in the rubber into the groove. I assume that for water shedding, their experimentation revealed that diagonal channels work best. So now they had to determine what direction of diagonal groove minimizes tread flex or deflection into the groove, or maximizes it if it was determined favorable, when the leading force is applied to the tread.
This optimization exercise resulted in the determination that grooving centre to outside in the direction of greatest force is best.
Phew Ottawa, I will re-read that when I have insomnia.
Traction = adhesive friction per the MW dictionary. I simply don't get how pointing the grooves the other way on the front tire increases it. Why don't racers use them instead of slicks if the traction is so much better? Why don't all front tires on bikes (and cages for that matter) utilize the idea? I am surely overly simplifying but what can I say? I'm simple minded.
No need to be a jerk about it. A lot of us have spent time out of our lives trying to explain it to you. It's no for our benefit. I will simplify even further than my last post:
Grooves are needed to shred water.
Grooves cause the tread block to deflect/flex.
This deflection impacts tire traction performance.
Strategically orienting the grooves is required to mitigate (reduce) the effect of the deflection.
They study the hell out of it and decide that when maximum directional force is placed on the tire, a tread groove that runs diagonally from the centre to the edge offers the better traction than grooves running diagonally from the edge to the centre.
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