Quick Tire Question Dunlop K81

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jnstrong

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Did a search and couldn't come up with anything.

Just put everything back together after a tranny rebuild and noticed after riding a day or 2 that the local biker shop that mounted my new rear tire put it on backwards. Dunlop K81s..so directional.

What is the harm in leaving it the way it is (rear tire set as it would be on the front)?

Thanks,
-Strong
 
They put it on wrong they can rectify it. Id not run it the wrong way
as I figure Dunlop knows more about tires than I do.
 
The rotation direction of a tyre is determined by the way the rubber is spliced onto the body of the tyre. It has to have a join around the circumference somewhere. That join is set at an angle to give the join more contact area. A rear tyre experiences more acceleration and a front tyre experiences more braking, so the tyre is put onto the rim so the acceleration of a rear wheel " pushes" the join together, and on the front, the braking "pushes the join together. If a rear tyre is mounted the wrong way round acceleration will try to pull the join apart.

Perceived wisdom is that it's better to leave a tyre mounted incorrectly if it's been on there for any length of time, but since yours has been only on for a couple of days, I'd ask them to turn it around.
 
Here's an example of the join separating

Quick Tire Question Dunlop K81
 
pommie john said:
Perceived wisdom is that it's better to leave a tyre mounted incorrectly if it's been on there for any length of time, but since yours has been only on for a couple of days, I'd ask them to turn it around.
Click to expand...
+1 and I'd go a little farther than merely asking that they turn it around; I'd be pretty insistent, since they may balk at it. They shouldn't, as they could open themselves up for some nasty lawsuit if that sucker were to come apart and dump you on the road. I'd hate to see that happen to you and your bike.
 
pommie john said:
The rotation direction of a tyre is determined by the way the rubber is spliced onto the body of the tyre. It has to have a join around the circumference somewhere. That join is set at an angle to give the join more contact area. A rear tyre experiences more acceleration and a front tyre experiences more braking, so the tyre is put onto the rim so the acceleration of a rear wheel " pushes" the join together, and on the front, the braking "pushes the join together. If a rear tyre is mounted the wrong way round acceleration will try to pull the join apart.

Perceived wisdom is that it's better to leave a tyre mounted incorrectly if it's been on there for any length of time, but since yours has been only on for a couple of days, I'd ask them to turn it around.
Click to expand...

You are quite correct, but you are referring to the inner casting which is joined, the outer tyre rubber itself is moulded onto the inner casting, the pic showing the outer tyre thread shows exactly what can happened when it is fitted the wrong way round :(
 
Bernhard said:
You are quite correct, but you are referring to the inner casting which is joined, the outer tyre rubber itself is moulded onto the inner casting, the pic showing the outer tyre thread shows exactly what can happened when it is fitted the wrong way round :(
Click to expand...


So what's separating in the two photos in this thread? It looks like the outer tread and I've seen tyres where this happened and they definitely look like the tread is spliced on with an angled join.
 
From Avon:

What is a tread splice? When a tire is manufactured the tread portion of the tire starts out as a long flat strip. This strip is wrapped around the tire and the two ends are cut on an angle so one end overlaps the other rather than having square cut ends.
This overlapping point or splice offers a bigger surface area to bond together, rather than the small surface area provided by square cut ends. (Imagine gluing your fingertips together, as opposed to gluing along the entire length of your fingers laid on top of each other. Like an angled splice, the overlapping fingers result in a much stronger bond).
To further ensure the strength of this bond along the tread splice the directional arrow will show you which way to mount the tire so that when the rider is “on the gas”; the acceleration force on the rear tire is pressing the splice together, rather than peeling it back.
 
pommie john said:
Bernhard said:
You are quite correct, but you are referring to the inner casting which is joined, the outer tyre rubber itself is moulded onto the inner casting, the pic showing the outer tyre thread shows exactly what can happened when it is fitted the wrong way round :(
Click to expand...

So what's separating in the two photos in this thread? It looks like the outer tread and I've seen tyres where this happened and they definitely look like the tread is spliced on with an angled join.
Click to expand...


The tyre carcase is as per Avon’s statement from pommie john.
The inner carcase is spiced at an angle –depending on the tyre manufacturer-on motorcycle solo tyres.
either the tyre has been put on the wrong way round, or the engine power has exceeded the tyre load limits, i.e. been run under a low pressure, or the wrong tyre for that bikes engine power, or some other reason.
Overloading and under inflation are the main cause of channel cracking

http://www.youtube.com/watch?v=Ka-NUSf2Exo
 
I don't quite where you get this bit about liquid rubber being injected into a tyre mould from.
As clearly stated in the Avon document and also shown in this video from Dunlop here (http://www.youtube.com/watch?v=OOYGXkRF2MY), all the rubber used in building a tyre is applied in flat strips to the carcass before this is placed in the mould for curing.

If you have ever been in a tyre factory, or seen uncured rubber, then it's fairly obvious why it's not injected.

/Steve in denmark
 
Mmm, you could be right, it is over 30 years ago since I went to the Avon tyre factory and was taken on a quick tour of how the tyres are made, I was only shown how the bike carcase was made and the car tyre moulding machine, so if you would kindly ignore my last post :D :shock:
 
OK, to sum up, do we all agree that since the tyre has only been on a couple of days it should be turned around to the correct fitment?
 
pommie john said:
OK, to sum up, do we all agree that since the tyre has only been on a couple of days it should be turned around to the correct fitment?
Click to expand...
Put me down for a "Yes".
 
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