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Discussion Starter · #1 · (Edited)
Apologies if this is a daft question but looking at the treads/groves on the CB500 range I'm trying to understand why the front tread/grove is facing in the direction of (^) and the rear is (v) in other words opposites.

I'm attempting to see how that would effect something like water dis-placement during wet riding. (Doubt it makes much difference in the dry).

Shouldn't they be facing the same direction to improve grip i.e (v) as per the rear tyre or has it got to do with downforce?

Not sure the picture clearly shows the two but worth a go (copied Malcolm O's bike picture - hope you don't mind, if so will remove it).
 

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Discussion Starter · #2 ·
..maybe this picture shows it from a better angle.
 

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I'm not sure about the rear. Maybe it allows for better bite in terrain that isn't solid?

As for the front it makes sense. It'll shoot the water out.
 

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Some guys just stopped me and said my front tire is on backward. Said the tread should be same direction as back to squirt water out. Going to call deler tomorrow see what they say
 

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Most motorcycle tires have a rotation arrow on the tire. Just search the whole sidewall on the tire.
 

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huh! google is your friend! The tires are designed this way. This is the best explanation I can find
Let me explain it this way. The part of the tire that is in contact with the pavement is stationary relative to the road surface. When the tire hydroplanes, it is no longer stationary relative to the road. So let's say the bike is moving at 55 mph. You hit a puddle that slows the front tire to 50 mph, while the bike remains at 55 mph. Now keeping the 5 mph difference, let's drop both speeds 50 mph. That would bring the bike to 5 mph and the tire to 0 mph. This would make the "reverse" tread come into effect. So you could look at it as a locked front tire sliding across the ground at 5 mph. Or you could drop the speeds 55 mph. Bringing the bike to 0 mph and the tire to -5 mph. Same principles apply
 

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Discussion Starter · #8 ·
Ok I think I get. More to do with the displacement of water on the front tyre under lock up or severe braking. i.e it forces water away from the front tyre to cause downforce so maintains grip and the opposite for the rear.
 

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I don't think about the rotation but the resistance to rotation that is imparted by the wheel. If it is the rear wheel, power is generated and the tire is resisting rotation and that interaction takes place in the treads contact with the ground. The front wheel brake is applied and the resistance to rotation acts in exactly the opposite direction for the front wheels tread contact. so pretty much the opposite rotation of the tire is used on the front to is better for steering.
 

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Althought I haven't thought much about it it seems logicall that the work in opposite ways:

1- The front tyre supports more weigh under branking, when you are reducing speed

2- The rear tyre under accelaration, when you are increasing speed!

I find logical they have opposite thread.

In a car although mass transfer exist is not as radical as on bike!

Does it make sense?
 

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Althought I haven't thought much about it it seems logicall that the work in opposite ways:

1- The front tyre supports more weigh under branking, when you are reducing speed

2- The rear tyre under accelaration, when you are increasing speed!

I find logical they have opposite thread.

In a car although mass transfer exist is not as radical as on bike!

Does it make sense?
You explained that exactly correct, amigo :)
 

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It rains twice a year where I live. I stay inside the house on those days.
I couldn't care less about tire grooves or hydroplaning.

:D
 

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In a car although mass transfer exist is not as radical as on bike!
More importantly:

On most cars these days, the drive is at the front wheels as well. So car tires cannot generally be optimized for drive or brake, because more often than not the tire has to be good for both. So most car tires are a compromise between the two.

Also, for convenience and simplicity, most cars are made with identical tires/wheels on all four corners. This allows tires to be rotated and swapped as appropriate. Again, tires are generally designed as a compromise: non-directional so they can be moved easily from side to side and a compromise between driving and braking capability.

On rear wheel drive performance vehicles you will sometimes see different front and rear wheel sizes and tire patterns. This is the exception because it makes things much more expensive and less convenient.
 
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I thought I'd try a detailed explanation with my own words, to see if you all agree :) Not different from what’s already been said, but just with other (more) words.:)

The difference between the front and the rear is as most here have explained correctly that the rear tire is the one pushing the bike forward against the surface while the front tire just rolls along.

If you have seen a tire on a glass plate you quickly see that the only thing that matters is the contact surface between the tire and the road/glass plate, and where the water in-between goes when it is pushed away. The surface area between the tire and road is very small, and the relative speed between them in the speed direction is generally 0. The only relative motion between the tire and road is up and down as new tire surfaces areas coming down on the new road areas as you drive. If you map spots on the tire with A, B and C they will hit the road at respectively spots A, B and C if all the spots are spaced out evenly. So at the contact area the grooves will be either be formed to lead the water outwards and forward or outwards and backward, ^ or v.

The back tire, with the driving force for acceleration, it is more likely to push the water in front of it, thus making it most sensible to have the grooves be formed to lead the water outwards and forward. If the back tire spins it will no longer have a relative speed of 0, but the tire area are now moving backwards relatively to the road so the water is now being pushed outwards and backward, thus removing even more water. The grooves are now acting as squeegees on the surface, throwing water outwards and backward.

The front tire is only being affected by the force from the water and the road, resisting the spinning direction, making it easier for the water to exit behind the tire rather than being pushed out forwards. Thus the grooves are formed to lead the water outwards and backward. If the front tire slows down it will no longer have the relative speed of 0, but the tire is now moving forward relatively to the road. But even with the front tires locked the grooves, because of leading the water outwards and backward, will still allow water to flow through the groves outwards and backward (instead of inward and backward towards the centre of the tire).

Does this make sense, or was it too much overthinking?:confused:

As for cars I think MichaelInVenice got it covered.:cool:

 
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