Front tire mounted backwards - Kawasaki KLR 650 Forum
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post #1 of 33 Old 07-03-2013, 10:15 AM Thread Starter
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Front tire mounted backwards

Just had the a dealer install my front shinko 705, and when I got to work i looked at it and the directional arrow on the tire is not pointing in the direction of travel. So they basically put it on backwards. They are willing to fix it, but does it need to be? what affects will i see, bad wet road riding.

Thanks,
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post #2 of 33 Old 07-03-2013, 10:50 AM
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Just had the a dealer install my front shinko 705, and when I got to work i looked at it and the directional arrow on the tire is not pointing in the direction of travel. So they basically put it on backwards. They are willing to fix it, but does it need to be? what affects will i see, bad wet road riding.

Thanks,
Less-than-optimum braking force from your reversed-rolling-direction front tire, IMHO.

The "Vees," front and rear, rotate opposite each other; the front to optimize BRAKING, and the rear to optimize THRUST.

I know, I know; then the rear does NOT optimize braking force. True. Consistent with the objective, the rear is optimized to make the bike GO, the front to make it STOP.

I have spoken.

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post #3 of 33 Old 07-03-2013, 10:54 AM
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All of the following is only my opinion, nothing more. Use at your own risk.

Some tires are truly directional. They are set up to work in one direction only and their tread is specifically set up to work in that direction, and those tires are used for either the front or rear only.

Those tires are usually rather high performance tires.

Tires like the 705, K761, Battle Wing, etc, are marked with a rotational direction arrow for use when the tire is mounted to the rear as a driving tire (and where you find a 21" rear wheel I dunno).

The logic in mounting such a tire 'backwards' on the front is that the front tire drives the bike backwards when it is working. It does that, of course, though the forces of braking.

By mounting the tire 'backwards' on the front you're actually mounting it so that it can work as designed under driving forces.

Let's go back to some high performance tires. If you look at the direction of the tread on the front versus the rear you will notice that they are asymmetrical to one another. In a high-performance application the designer specifies the tread pattern for the front and for the rear, and the direction of rotation for each tire.

Is all this 'backwards' mounting a crock and a mistake? I don't know, but that's my story and I'm sticking to it.

As a side note, the first time I used a K761 on the front is started cupping badly after a few thousand miles. I put it on backwards and the cupping stopped. The next time I mounted the tire backwards from the start and it never cupped, nor has any one since.

T

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Last edited by Tom Schmitz; 07-03-2013 at 11:21 AM.
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post #4 of 33 Old 07-03-2013, 11:17 AM
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Damocles and I posted at about the same time, he having been more succint and quicker than I.

I beleive that your installer has done the right thing.

If the tire has a notation on it that says "Front Only" and it has been installed with the rotation arrow the wrong way, that would be incorrect. I don't believe that your tire is "Front Only", though.

Here are some pictures of a pair of Michelin PR2s.

Note the direction of the "V" here on the rear:


And the direction of the "V" on the front:


These tires are directional:



I think you've got a knowledgeable installer.

T

Tom [email protected]

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post #5 of 33 Old 07-03-2013, 12:11 PM
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I'd double triple confirm all the above.

Tires on a bike may be different than tires on a car, but tires in general all have tread patterns designed to grip road surfaces, while dispelling anything that would cause the tire to lose traction with the road - like funnelling water away.
Particularly in the sense of water, I could see a tire mounted backwards pulling water under the tire rather than pushing it out from under the tire, and hydroplaning on a motorcycle... I don't ride in the rain, but that doesn't sound safe.

From mounting my directionals on the incorrect corners of my car, I can tell you that they will pull, they are noisy, and are dangerous on anything but a clean, dry road surface - and even still I wouldn't want to bring them up to their rated speed.

Now, if the tire is ENGINEERED to be run backwards on the front - that certainly would be a different story. In that case, I'd expect to see not just a directional arrow, but one with "front" and "rear" designations like the tire Tom shows above.

If you don't see that special designation - I'd have the shop put them on right. It could be (like most shops), they've got some kid doing the menial work in the garage, and he just slapped the tire on between Facebook posts on his smartphone.
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post #6 of 33 Old 07-03-2013, 12:47 PM
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Car tires and bike tires are two different animals.

At any rationale and normal speed, you cannot hydroplane a round-profile tire. This is primarily due to the canoe-shaped contact patch. It can't be done on a bicycle, motorcycle, or a racing wheelbarrow. Car tires, with a rectangle contact patch and square-on edge to the water, can and do hydroplane as they build up a standing wave of water in front of the contact patch. That wave can lift the tire.

The tires in question are inexpensive tires that share a carcass across several styles of tread, e.g the K761 and the K270 very likely share the same carcass. The molds are designed and simply scaled up or down. The tires themselves can be run in either direction with no impact on the carcass. The simple fact is that there was not a lot of effort put into making them directional.

Empirical evidence does show that front tires mounted with the arrow going in the direction of rotation tend to cup and logic would indicate that is from the driving forces on the tire being counter to the designed driving forces.

T

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Last edited by Tom Schmitz; 07-03-2013 at 12:50 PM.
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post #7 of 33 Old 07-03-2013, 01:28 PM
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Originally Posted by Tom Schmitz View Post
Car tires and bike tires are two different animals.

At any rationale and normal speed, you cannot hydroplane a round-profile tire. This is primarily due to the canoe-shaped contact patch. It can't be done on a bicycle, motorcycle, or a racing wheelbarrow. Car tires, with a rectangle contact patch and square-on edge to the water, can and do hydroplane as they build up a standing wave of water in front of the contact patch. That wave can lift the tire.

The tires in question are inexpensive tires that share a carcass across several styles of tread, e.g the K761 and the K270 very likely share the same carcass. The molds are designed and simply scaled up or down. The tires themselves can be run in either direction with no impact on the carcass. The simple fact is that there was not a lot of effort put into making them directional.

Empirical evidence does show that front tires mounted with the arrow going in the direction of rotation tend to cup and logic would indicate that is from the driving forces on the tire being counter to the designed driving forces.

T
I never thought why bikes don't hydroplane. Thanks Tom. I feel smarterer now.




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post #8 of 33 Old 07-03-2013, 01:40 PM
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I have had my 1500 Vulcan hydroplane at reasonable speed (45mph) on the highway in moderately heavy rain. Dont get a false sense of security by the previous statements in this thread.
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post #9 of 33 Old 07-03-2013, 01:43 PM
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Originally Posted by Tom Schmitz View Post
Man, that's a lotta lead!
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I think you've got a knowledgeable installer.
Really? You mean, he PURPOSEFULLY installed the front tire BACKWARDS?

Just askin'!
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post #10 of 33 Old 07-03-2013, 01:53 PM
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I have had my 1500 Vulcan hydroplane at reasonable speed (45mph) on the highway in moderately heavy rain. Dont get a false sense of security by the previous statements in this thread.
Ride Safe....justjeff
Did you survive the subsequent crash? :^)

I ask that because if you truly did hydroplane the bike the front end would have quickly washed out and the whole thing went FDGB.

The front tire is constantly weaving in and out of a true straight ahead direction. If it is hydroplaning it isn't touching the ground, thus there is no traction and no force to correct the tire's track back in the opposite direction of the weave.

Now, I will admit that once I was riding up I5 in a heavy downpour right after they had chip sealed the road. The rain and the truck traffic had mixed the water, dirt and oil into an awful mess that coated me and the bike from head to toe. It was all good except for the road under the underpasses, where this muck couldn't get washed away. Every time I hit it the back end of the bike would get a bit squirelly for a few feet. That's not hydroplaning, though, any more than not having traction in gumbo is hydroplaning.

I'll allow for the fact that you may have hit some goo, oil, or black ice, but remain unconvinced that it was hydroplaning.

As ever, I am open minded and will be happy to consider any proof that doesn't rely on data and formulae for flat-tread tires.

T

Tom [email protected]

“Neither of the two people in the room paid any attention to the way I came in, although only one of them was dead.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte


Sting like a butterfly.

Last edited by Tom Schmitz; 07-03-2013 at 02:08 PM.
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