Bike tyres tread direction.

[jinbok]

Few of my friends are arguing over tyres tread direction of certain tyres,
rather than going to the LBS, I decided to post them up here.


Is this tyre mounted correct tread direction?
It looks like tread pattern is going opposite of tyre's rolling direction.

[ltwtsculler91]

Had this discussion in the shop on Friday installing some new Pirellis..

Any "modern" treads are usually labeled with a direction on the side wall, which seems to affect wet weather handling. That said, we've seen GP 4 Seasons labeled in both directions

File treads sides like these, can go either way but everyone seems to have a personal preference as to what is "right." Personally I'd say yours are backwards, since I like the "arrow" formed pointing in the direction of travel

[Cicli]

Those dont matter. Lable on drive side, lined up with valve stem.
Unless you ride Veloflex or are Weisan.

[Black Dog]

Tread and having tread direction are both irrelevant on road tires. Treads are decorative at this small scale.

[R3awak3n]

Does not matter but I would have mounted it the other way just because I see those lines as arrows but if they were mounted already I would be too lazy to flip them.

[R3awak3n]

oh and because those are compass tires

straight from the makers mouth

[dddd]

Most people would let the tire manufacture test and decide for them instead of making assumptions based on theory, but mtb'ers have been known to test running their rear tires in both directions to try for more-preferred traction characteristics.

With road-going tires, usually it is the vector or force-direction arrow from combined braking and cornering which is directed to cross channels and lugs in the tread pattern. This as opposed to having the force directed along channels and lengths of tread element. Reason for this is to force bits of gravel to cross the tread features such that a rolling stone of gravel does not continuously lift the taller tread elements and thus the contact patch off of the roadway. The rolling action is thus interrupted by having to cross channels in the tread, which can prevent abrupt slide-outs under certain conditions of gravel size, loading, cornering and tire pressure.

Road-going motorcycles typically orient their tread blocks in opposite fashion, so as to prevent tread elements from yielding too much (tread squirm) due to their much greater height controlling the steering/cornering loads of a heavy motorcycle.
Most motorcycle dirt bike tires have an opposite sort of pattern that is more like a bicycle tire!

So look for a forward-facing chevron on a bike tire, and a rearward-facing one on a road-going motorcycle tire.

I find it useful to place my hand above a bicycle tire and point a finger forward and to the left, then look at the left side of the tread that actually contacts the road during cornering. I am looking for my finger pointing across any broad tread elements and channels in the tread instead of pointing more lengthwise with them.
Using this method for instance can actually save me the time of looking for the hidden arrow on the side of an all-black GP4000 tire, since I can always guess which way the tire should rotate.

The fine tread of the Compass tire pictured would not be directional, since the tread elements are too small and because the "directional" rows are finely staggered. Testing under a specific set of conditions might show differences from one direction versus the other, but would be subject to so many near-infinite variables so as to be moot.

[Mark McM]

Originally Posted by dddd

Most people would let the tire manufacture test and decide for them instead of making assumptions based on theory, ...

This is an ironic statement, since there is no publicly available evidence that manufacturers do anything other than make their own assumptions.

Some manufacturers have claimed that the small patterns found on road tire tread improve traction. Other manufacturers have claimed that smooth tread tires have the best traction on pavement. As far as I'm aware, the only manufacturer that has actually provided any evidence (such as test data) is Avocet, when they introduced their FasGrip brand tires, which were all had slick treads.

There have been independent tests of tire traction done. These tests have included a range of commercially available tires, both smooth and treaded. While these tests were not specifically intended to test the affect of tire tread, looking at the results there is no clear trend that tread patterns (or lack thereof) makes a difference.

Continental is one company that has publicly stated that tire tread doesn't matter on pavement. Some of their tires have small tread imprints, but these grooves are small enough and far enough apart that the tires might as well be smooth. It is true that many Continental road tires have directional arrows. When a Continental engineer was asked about this, he admitted that the reason they add directional arrows is because they got many customer inquiries about tire direction, so putting arrows on the tires was done to reduce the number of customer service calls they get.

Until a tire manufacturer is willing come out and show hard evidence that tire tread improves traction on pavement (wet or dry), or that tread direction matters, I'll continue to assume that tread is just a marketing feature.

[Black Dog]

Originally Posted by Mark McM

This is an ironic statement, since there is no publicly available evidence that manufacturers do anything other than make their own assumptions.

Some manufacturers have claimed that the small patterns found on road tire tread improve traction. Other manufacturers have claimed that smooth tread tires have the best traction on pavement. As far as I'm aware, the only manufacturer that has actually provided any evidence (such as test data) is Avocet, when they introduced their FasGrip brand tires, which were all had slick treads.

There have been independent tests of tire traction done. These tests have included a range of commercially available tires, both smooth and treaded. While these tests were not specifically intended to test the affect of tire tread, looking at the results there is no clear trend that tread patterns (or lack thereof) makes a difference.

Continental is one company that has publicly stated that tire tread doesn't matter on pavement. Some of their tires have small tread imprints, but these grooves are small enough and far enough apart that the tires might as well be smooth. It is true that many Continental road tires have directional arrows. When a Continental engineer was asked about this, he admitted that the reason they add directional arrows is because they got many customer inquiries about tire direction, so putting arrows on the tires was done to reduce the number of customer service calls they get.

Until a tire manufacturer is willing come out and show hard evidence that tire tread improves traction on pavement (wet or dry), or that tread direction matters, I'll continue to assume that tread is just a marketing feature.

100%. Without more data it is irrational to assume that tread matters. The only available data points to there being no difference then tread is likely just something nice to look at.

[Jan Heine]

Originally Posted by Mark McM

provided any evidence (such as test data) is Avocet, when they introduced their FasGrip brand tires, which were all had slick treads.

Avocet tested on a steel surface whether tires hydroplane. Their finding was that they don't, and from that, they concluded that tread doesn't matter. But unfortunately, that was asking the wrong question, and their tires offered phenomenally poor wet-weather grip. They are the only tires I could spin when pulling away from traffic lights, not just once, but repeatedly!

Michelin also appears to have done some testing. I found a reference to that in a 1980s or 1990s Bicycle Science Newsletter article by a Michelin engineer. He mentioned that it's not the evacuation of water, but the interlocking of road surface and tread pattern, that matter.

My own, somewhat unscientific testing, seems to confirm the assertions of the Michelin engineer: I've ridden both shaved-down Grand Bois tires (tread removed) and Compass tires (chevron tread). Even though I rode the shaved tires only for a few hundred miles in the rain, I crashed twice. I've riden thousands of rainy miles on the chevron tread without crashing. n=2 is small, and it could have been that I just happened to hit very slick spots by coincidence on those few rainy rides that were on slick tires, but I don't think so.

When you look at the wet coefficient of friction of rubber on stone (the aggregate in the pavement), it's only 30% or so of the dry value. And yet every cyclist knows that you can corner with more than 30% of the dry-weather speed in the rain - it's more like 50-70%. The difference comes from interlocking of the tire with the road surface. Some argue that it's the road that is imprinted on the tire, and thus the tire tread doesn't matter, but my experience indicates that fine ribs that provide multiple edges to interlock with the road irregularities make a significant difference. I do agree that treads that are inspired by car tires, or those that sipes and scallops that come companies put onto their tires probably don't do much - there are too few surfaces to interlock.

Testing this under controlled conditions is extremely difficult. TOUR magazine in Germany first tried to drag a wheel behind a car and turn it sideways until it slipped. That didn't give repeatable results, so they built a scooter and had a stuntman ride it around a curve on ever-tighter lines until he crashed. Even that wasn't conclusive - one problem they had was that with a deadline, they had to test when the first rain happened, rather than wait for a few days until the road surface was washed clean and thus more uniform. It seems that finding uniformly wet pavement is very difficult. The only way around that is to ride thousands of corners with different tires and count crashes, and then look at the statistics. Which is basically what I have done, but probably not enough to get statistically significant results. But then, crashing on the open road is too dangerous to do just in the name of science. So I stopped riding slick tires and haven't crashed since.

Jan Heine
Founder
Compass Cycles
www.compasscycle.com

[carpediemracing]

As far as mountain bike and motocross tires go, there's low enough grip in certain situations (mud, loose dirt, root) where tread direction will make a difference. Heck, simply having tread will make a difference.

The typical set up I used (and those around me, including much better riders) was to set up the front tire to stop better (chevrons facing forward when on top of the tire, reverse when on the ground) and the rear tire to grip better when climbing steep/loose stuff (chevron facing backward when on top of tire, reverse when on surface).

The idea was that you wanted the tire to be maximized for the highest stress situations where you wanted the tire to grab. Up front it was steering and stopping. In the back it was having traction when trying to put power to the ground in a super low gear.

I believe the tires were marked, at least some of them. The tires to have around here were the WTB Raptors, very directional both front and rear.

As suspension started to make its way into mountain biking I started experimenting with narrower higher pressure tires, and typically those tires didn't come in the super aggressive/specialized tread patterns. That's about when I stopped riding off road.

[carpediemracing]

On road... I just put the label on the right side, and the chevrons pointing forward if there are labels on both sides. Label placement is probably the most critical thing for me when mounting road tires.

[oldpotatoe]

Originally Posted by Cicli

Those dont matter. Lable on drive side, lined up with valve stem.
Unless you ride Veloflex or are Weisan.

Funny...once upon a time, long time ago, with Vittoria CGs..we installed front 'correctly' but rear 'opposite'..cuz along with red glue, thats what ya did..

In the 'grand scheme of things', it means not much. Yup, if the tire had an arrow, I installed correctly, but mostly so customer wouldn't come back and..'is this tire on right?'

[merckx]

Originally Posted by oldpotatoe

Funny...once upon a time, long time ago, with Vittoria CGs..we installed front 'correctly' but rear 'opposite'..cuz along with red glue, thats what ya did..

In the 'grand scheme of things', it means not much. Yup, if the tire had an arrow, I installed correctly, but mostly so customer wouldn't come back and..'is this tire on right?'

Our method was CX up front, a CG in the back, and a tattered whatever strangled with a Binda beneath the Regal.

[zap]

edit

Originally Posted by Jan Heine

Avocet tested on a steel surface whether tires hydroplane. Their finding was that they don't, and from that, they concluded that tread doesn't matter. But unfortunately, that was asking the wrong question, and their tires offered phenomenally poor wet-weather grip. They are the only tires I could spin when pulling away from traffic lights, not just once, but repeatedly!

Some of Mavic's recent tires are super slippy in the wet.

Your comments on Avocet tires brought back some memories. I used to race crits on a set........super sticky. Could corner like nothing else but hate to think what the rolling resistance was.