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Old March 26th, 2018, 09:37 PM   #1
Spaghettiknight
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Front tire tread direction

I bought a pair of Shinko sr740/741. They were a good price and had decent reviews. I mounted the front tire a couple of days ago (after ALOT patience and elbow grease) I made sure I had the direction of rotation right as I did not want to have to endure the procedure again, but after having a buddy mention something today, we noticed the tread makes it look like the tire is mounted in the wrong direction.

I attached some pictures of the new tire and old tire next to each other and with the arrows for direction of rotation next to each other. I was wondering if anyone has ever heard of a motorcycle having tread looking like it would direct water into the tire for any reason? I'll give Shinko a call and update with what they say but just seems bizarre to me.
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Old March 26th, 2018, 09:55 PM   #2
Triple Jim
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I'll be interested in Shinko's answer.

If mounting the tires was difficult, you probably need to do a better job keeping the beads in the drop-center part of the rim everywhere that you're not working with the irons. I've had cases when it helps to get someone to stand on the tire to keep the beads squeezed together while I work with the irons. Also lots of good lube is important.
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Old March 26th, 2018, 10:04 PM   #3
Spaghettiknight
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That's exactly what i had to do but it was still very difficult. had 3 guys working on it, one holding an end with an iron, the other standing on the back end to get the tire already over toward the middle so it could stretch, and finally someone lubricating and pulling at a little chunk of the bead. I also had the tire heated up next to a fireplace to probably around 130-140 fahrenheit. I did not think it was going to be that difficult but I guess the rubber for the tire must be more stiff than most sport tires.

I posted a picture of where it started to get tough, i thought there was no way but we managed to get it over there with 3 guys doing those jobs.
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Old March 26th, 2018, 11:11 PM   #4
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Quote:
Originally Posted by Spaghettiknight View Post
I bought a pair of Shinko sr740/741. They were a good price and had decent reviews. I mounted the front tire a couple of days ago (after ALOT patience and elbow grease) I made sure I had the direction of rotation right as I did not want to have to endure the procedure again, but after having a buddy mention something today, we noticed the tread makes it look like the tire is mounted in the wrong direction.

I attached some pictures of the new tire and old tire next to each other and with the arrows for direction of rotation next to each other. I was wondering if anyone has ever heard of a motorcycle having tread looking like it would direct water into the tire for any reason? I'll give Shinko a call and update with what they say but just seems bizarre to me.
Assuming the average motorcycle tire is spinning between 600 and 700 R.P.M at 60 miles per hour I don't think water is inclined to "build-up" on the moving tire tread. All the groves are there for is to allow water to squeeze out from under the tire, prevent "hydroplaneing" and allow rubber to stay in contact with the road surface. I think it matters more that there are groves than in what direction the groves are cut.

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Old March 26th, 2018, 11:43 PM   #5
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Yeah, due to lenticular shape of contact patch and higher pressure (relative to autos), motorbike tyres do a much better job of cutting through water. You'd have to go 100mph+ to start aquaplaning. Whereas in autos, that starts around 60mph.

On track with DOT-R tyres with minimal tread, I can get up to about 75-80% of dry speeds. Then go with rain tyres if i want to go faster.

The reason for the backwards appearing tread is for grip at contact patch. Roll tyre and watch tread block roll under. Combined vector of travel direction and centripedal cornering force pushing in from outside will be inline with long-axis of tread block. Mounting tread other way will result in cornering forces pushing across short-axis of tread block and less grip.

I remember when these Metzler tyres came out 30+ years ago with their "backwards" tread. But it really works better that way.

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Old March 27th, 2018, 12:07 AM   #6
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Yeah, due to lenticular shape of contact patch and higher pressure (relative to autos), motorbike tyres do a much better job of cutting through water. You'd have to go 100mph+ to start aquaplaning. Whereas in autos, that starts around 60mph.

On track with DOT-R tyres with minimal tread, I can get up to about 75-80% of dry speeds. Then go with rain tyres if i want to go faster.

The reason for the backwards appearing tread is for grip at contact patch. Roll tyre and watch tread block roll under. Combined vector of travel direction and centripedal cornering force pushing in from outside will be inline with long-axis of tread block. Mounting tread other way will result in cornering forces pushing across short-axis of tread block and less grip.

I remember when these Metzler tyres came out 30+ years ago with their "backwards" tread. But it really works better that way.

Thanks. That explanation make a-lot of sense. Looking at my Pirelli MT75's they sort of do that/look like that, just less pronounced. By the way, the MT75s are very "sticky" in the wet but may only be a two season tire at 1,600 miles per year.

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Old March 27th, 2018, 06:29 AM   #7
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I don't think there's any question as long as you mounted them in the direction recommended by the manufacturer.

I wouldn't go by the tread design of the old original tire. Compounds and tread patterns have come a long way since that was designed.
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Old March 27th, 2018, 06:45 AM   #8
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It’s always in the direction of travel arrow ! Imagine that wheel laid over in a turn then you will see it’s right.

For the tyre fit, be sensible & use a machine modern tyres have much stiffer sidewalls & really need a tyre fitting machine. If you insist ondoing it by hand then search YouTube for big cable tie tyre fitting or use rope tourniquets which you can re use.
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Old March 28th, 2018, 02:31 PM   #9
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Here's cool article on vintage tyres and vintage bikes:
https://www.webbikeworld.com/metzeler-lasertec-tires/
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Old March 29th, 2018, 11:36 AM   #10
Spaghettiknight
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Thanks for all the advice and replies. I Got the rear tire mounted (much easier since there is more rubber to work with) and got them both balanced and mounted so I really hope I don't have to pop off the front again. The Shinko US distributor manager got ahold of me and said that he believes it could be a misprinted tire as well. He said he will get ahold of the factory that produces them to confirm though. Very pleased with the service so far however. He said that if they had a more expensive tire available in the same size he would have paid to have them swapped out, but they did not. So i'm pretty confident he'll reimburse me if the tire needs to be remounted.

I'll keep everyone updated but for now i'll just avoid hitting water at high speeds, should be doing that anyway I guess...
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Old March 29th, 2018, 12:04 PM   #11
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Quote:
Originally Posted by Spaghettiknight View Post
Thanks for all the advice and replies. I Got the rear tire mounted (much easier since there is more rubber to work with) and got them both balanced and mounted so I really hope I don't have to pop off the front again. The Shinko US distributor manager got ahold of me and said they he believes it could be a misprinted tire as well. He said he will get ahold of the factory that produces them to confirm though. Very pleased with the service so far however. He said that if they had a more expensive tire available in the same size he would have paid to have them swapped out, but they did not. So i'm pretty confident he'll reimburse me if the tire needs to be remounted.

I'll keep everyone updated but for now i'll just avoid hitting water at high speeds, should be doing that anyway I guess...
Yep!!!!

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