tire tread direction

[alex.s]

i was just talking to a mechanic about tires and he told me something interesting.

he said that the direction of a tire doesn't matter if it is dry. the direction is purely for the tread pattern-- ON WATER. so that it pumps the water out to the side instead of toward the center if its going backwards. he said, if you are in the dry, tread pattern -- including the internal ply pattern -- does not matter. it only matters in the wet he said.

i had always heard (without real reason) that you can't have them backwards because it would rip the plys apart or some ****. he said that was BS. so now i'm curious. was he full of ****?

[csmith12]

No, I have run them in both directions for years.

[Alex]

I would agree on the tread pattern re: dry vs. wet. If it's not pumping water, it's not doing much.

But the front tires are designed for strong braking forces, while the rear tires are designed for strong acceleration forces. On a bike like ours, it's not going to matter much in almost all conditions (not braking from 150+, accelerating with < 35hp). But on a superbike, braking at max capability from high speeds, or accelerating with 150+ hp to the rear wheel, the forces are great enough to abuse a tire not made for it. Some slicks are specifically made to allow for flipping, others aren't. I don't think it's black and white enough to state that it will always be OK and not to worry about it. For some tires on some bikes, it could really be a problem.

[Whiskey]

The thread pattern is the main thing, in therms of internals I presume Radials would hold up better to flipping than bias ply, whose layering may be designed to work better in one direction than the other.

[alex.s]

Originally Posted by Alex

I would agree on the tread pattern re: dry vs. wet. If it's not pumping water, it's not doing much.

But the front tires are designed for strong braking forces, while the rear tires are designed for strong acceleration forces. On a bike like ours, it's not going to matter much in almost all conditions (not braking from 150+, accelerating with < 35hp). But on a superbike, braking at max capability from high speeds, or accelerating with 150+ hp to the rear wheel, the forces are great enough to abuse a tire not made for it. Some slicks are specifically made to allow for flipping, others aren't. I don't think it's black and white enough to state that it will always be OK and not to worry about it. For some tires on some bikes, it could really be a problem.

ever heard of an actual failure caused by this?

[Alex]

I'd have to search, but the most recent is all of the pirelli tire failures in F1 last year when teams mounted them opposite to how Pirelli required. (one link). That evidently had to do with the sidewalls being different on the inside and outside, so not directly applicable to m/c tires, but I'll see if I can find some failures there as well. I'd agree with @Whiskey, perhaps radial construction is somewhat less prone to these issues than bias-ply, but I wouldn't think they would be immune. Radials don't run the plies exactly 90 degrees from the rotation; they are still biased a bit depending on the construction.

[csmith12]

For me, it's a per set of tires judgement call. Knowing the history of the tire and previous feel goes a long way. Also, where I am riding on them plays a large role too. I am more prone to flip them at the track.

[Alex]

Some links:

gixxer! (someone talks about a tire peeling on track) :http://www.gixxer.com/forums/showthr...03&postcount=4

Here's what Avon has to say about it:

http://www.avonmoto.com/download/Tires_101.pdf

[cuong-nutz]

I decided to call Pirelli Tech support since I couldn't find a number for Bridgestone. He said you can but it's not recommended as the tire could peel away due to the directional weaving of the plies. I asked if he could find some literature to back up his statement and he said he'll email it to me when he does.

[rojoracing53]

On the Superbikes we would flip the UK made Dunlops all the time, both the dot and slick compounds with no problems now the US made Dunlops are a whole different story. I believe I've seen pics of US made Dunlops splitting at the segment seems on the rear tire but it could have just been a fluke because it seemed to me that tire would have separated in ether direction. I had a policy to never touch a US made tire after several very close calls and one bad crash. I recently tried to save $30 and go with a US tire(that's all you get in the US these days) and the thing cold cracked right down to the cords so again I'm steering clear of US Dunlops.

[csmith12]

Originally Posted by rojoracing53

the thing cold cracked right down to the cords so again I'm steering clear of US Dunlops.

For realz yo!

When I came back from Jennings, a few of my fellow track ho's (5 riders to be exact) where on US dunlops. They cracked down to the cords like ice cubes in hot water, just like you said. It wasn't pretty at all... I can dig up pics if ya need.

I gave Ally warning but interestingly enough, one of those 5 riders were running their tires backward. They ran all weekend just fine in I(B) group, it wasn't until they got back to OH, in the cold weather that the cracking became a major (show stopper/new tires) issue.

This is interesting stuff. Mostly new to me as well.

[alex.s]

Such interest

[csmith12]

Good question Alex.

[rojoracing53]

100 miles on the street and one session on Laguna Seca. I was lucky Pirelli was there to save my ass with a good used takeoff for $40 which was awesome on track and continues to be so on the street.

[rojoracing53]

I've been saying it for 10 years and will continue to even now. USA made Dunlops are crap.

[alex.s]

christ. what the **** is that massive crack in your tire

[rojoracing53]

Oh in case your wondering about the Rosso rear for our bikes. I was told most the races flip the Rosso with no problems and I did two days the correct and two days flipped and the tires looks great. Is still currently backwards and it'll stay the way till its dead.

[rojoracing53]

Originally Posted by alex.s

christ. what the **** is that massive crack in your tire

That's basically what I said as I was brushing off the gravel to put my warmer back on and saw the horizontal crack. Then after looking harder it was look holy **** it keeps going, and damn are those the white cords I can see at the bottom

[alex.s]

you didn't notice anything different when you were riding on that massive crack though? that's the part that seems scary to me.

[rojoracing53]

Originally Posted by alex.s

you didn't notice anything different when you were riding on that massive crack though? that's the part that seems scary to me.

No you won't feel anything from just the crack. After awhile it can start to peel like a sticker or other odd things and you feel that.

[alex.s]

[rojoracing53]

The good thing about running Warmers is after every session you need to wipe the gravel off the tire before wrapping them. This makes it easy to spot any issue ASAP.

[alex.s]

i think i'll start only buying bridgestones now... and i think i'll start running tire warmers...

[Alex]

Originally Posted by rojoracing53

I've been saying it for 10 years and will continue to even now. USA made Dunlops are crap.

It's been well documented that they've been crap for years, but supposedly things have changed recently. The same machines they were using in the UK are now up and running in the US, so theoretically the tires should be of similar quality. Hard to say for sure, but it will certanily take people quite awhile to come around based on past experiences.

[rojoracing53]

Originally Posted by Alex

It's been well documented that they've been crap for years, but supposedly things have changed recently. The same machines they were using in the UK are now up and running in the US, so theoretically the tires should be of similar quality. Hard to say for sure, but it will certanily take people quite awhile to come around based on past experiences.

The date code on this Dunlop is the 51 week of 2013 so I doubt anything has changed. Call me a communist but I don't trust anything made in the USA for quality in general, there are exceptions but not many.

[CycleCam303]

Pfft Dunlops. Pirellis all day every day.

[mgentz]

Originally Posted by csmith12

No, I have run them in both directions for years.

On one side turn heavy tracks, I would flip my tires all the time to wear down the other side. Saves $$$.