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I have a mountain bike tire that has stamped on the side something like:

<----------front rear------------->

Which seems like a pretty clear indication that the tire should be oriented in one direction when used in the front, and the opposite when used in the rear. Is that right? This is counter intuitive to me - I would have expected tire tread to face the same direction on both wheels - like cars.

If so, is this true in all cases? For example, road bike tires with tread to handle rain?

And finally...why?

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Thank you for this discussion. I am a winter rider and I'm putting my winter studded tires on my hybrid bike I use in the city. Last year was the first time I rode in the winter and was amazed how well studded tires worked on ice, snow, whatever. I never even felt I was in danger of sliding or going down. Now that I am about to mount them again I realize I dont really know which way they go. After reading this I gather the front and rear should go opposite ways but am not totally clear on how the rear tire should go. I assume the >>>>>>> part of the tire should be the first to come into contac –  user3074 Dec 18 '11 at 8:14
    
I did find on the tires the directional arrows spoken of, but unless there is a specific front and rear tires, and the front and rear tires are suppose to go in opposite directions, what difference will the arrows on the tires make? –  user3074 Dec 18 '11 at 8:20
    
Unless there are two arrows -- for front and rear -- then it likely doesn't make much difference in terms of tread. However, the direction of rotation may make a difference with regard to the cord in the tire, especially on very lightweight tires, so it's still worthwhile to observe whatever arrows are present. –  Daniel R Hicks Dec 18 '11 at 13:22
    
The simple answer is to follow the instructions. If it there are separate front and rear arrows then follow them, if there's just one direction do that, and if there is none then it doesn't matter. The arrows should be pointing in the direction the tires rotate in, so when you have them mounted and you move the bike forwards, the arrows should appear to go with the tire. Different tire patterns require different setups, but they should all be documented sufficiently on the side wall. –  Colin Newell Dec 18 '11 at 16:55

7 Answers 7

The tires have more traction in some directions than in others.

Your front wheel does most of the braking; your rear wheel does all of the propulsion.

Tires are oriented to give the most traction to the primary fore-and-aft forces.

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The < > layout is the most common. As Jay Bazuzi pointed out, the forces on the tires aren't from the same directions.

Some tires it doesn't matter, some it does.

Also, road bike tires typically have essentially zero tread, and it doesn't matter which way they are mounted. They'll almost always have a "rotation ->" printed on them though, but thats really just so people don't get confused, especially mechanics that are so used to looking for those when mounting tires.

Lastly, bike tires don't need tread to handle rain.

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"Bike tires don't need tread to handle rain." Excuse me? Since when? –  Neil Fein Dec 30 '10 at 15:34
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@neilfein: since always. Unlike car tires, with their flat profile which does need tread for rain, bike tires have a curved profile which makes it practically impossible to hydroplane. Even with slicks. sheldonbrown.com/tires.html#hydroplaning I'd appreciate removal of the -1 –  whatsisname Dec 30 '10 at 18:13
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Sheldon Brown makes great points in the section, "Tread for on-road use". @whatsisname - I upvoted your answer. –  user313 Dec 30 '10 at 18:22
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Especially, "People ask, "But don't slick tires get slippery on wet roads, or worse yet, wet metal features such as expansion joints, paint stripes, or railroad tracks?" The answer is, yes, they do. So do tires with tread. All tires are slippery in these conditions. Tread features make no improvement in this." –  user313 Dec 30 '10 at 18:23
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@whatsisname - I misunderstood your point; I thought that you meant bikes didn't need to handle rain! I have slick tires that handle very well in the rain. –  Neil Fein Dec 30 '10 at 22:14

My road tires with a light tread have the sense of direction indicated much like a car tire, so that water gets channeled outwards from the center to the outside. I guess theoretically mounting your tires the wrong way round may slow you down?

Concerning if tread has any effect on bicycle handling, when it is cold and there is loads of crap on the road (slushy snow) it certainly does make a difference as I found out when I swapped my old tires for new ones (same make/model).

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It might slow you down, but I think the bigger difference will be loss of traction due to hydroplaning (noticeable under hard cornering or breaking). –  Dana the Sane Jan 2 '11 at 2:44
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No, you really can't hydroplane on a bike. Tire's too narrow, speed's too low, and bike tires have a narrow pointy contact patch compared to a car's rectangular contact patch. The hydroplane limiting features on a car's tire tread are the width of your bike tires and you're going much slower. Some of the treads on bike tires are designed to limit how much water is picked up or to throw it in a less annoying direction, though. –  freiheit Jan 2 '11 at 6:55
    
I've found that with some directional mountain bike tires, fitting the rear tire backwards means that your back wheel slides out from under you when you turn sharply. I normally discover this when riding out from the drive and onto the road. –  Colin Newell Dec 18 '11 at 16:58

If you ever drove a farm tractor you'd understand. Some tires have a "directional" tread -- effectively >>>>> or <<<<<<. Now, you might expect that a tread of <<<<< would have better traction if you were attempting to pull it to the right (and it were resisting the pull by trying to go left), but that's not the case. The <<<<< tread will "load up" with mud/gravel/whatever when pulled to the right (and traction will be reduced to near zero), but if pulled to the left it will be "self cleaning" and traction will be an order of magnitude better.

On the rear tire, obviously, you want the best traction when pedaling -- to move the bike forward. On the front tire, on the other hand, you want the best traction when braking. Thus the tires would be installed in opposite directions.

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I like the 'loading up' explanation for why this is counter-intuitively true. Much appreciated. –  Ehryk May 9 '12 at 0:00

This is a much debatable topic, but some "facts" should be considered.

First, as Grant Petersen (from Rivendell Cycles) pointed out in his text, for hard, paved roads the best tread pattern is zero, because the tire rubber deforms around the asphalt or concrete texture, and so the zero-thread offers a greater total area of rubber-pavement surface to interlock.

The extreme opposite, the super-knobby MTB tires, are intended to use off-road, where the surface deforms, having a visco-plastic mechanic behaviour. Instead of only the tire rubber conforming to the road texture, actually the soft terrain is indented and "flows" around the tire knobs, which are required to transmit reaction forces to the ground without slipping, while tractioning, braking and cornering.

In the middle, we have all other kinks of pavement (sand, gravel, hard-pack) and thread patterns (grooved, semi-slick, etc.)

In my experience the directional pattern is only found in Mountain Bike tires intended to be used off-road or in specific kinds of trail terrains. There are tires with a single directional pattern that should be inverted between front and rear. There are tires whose rear-front pair are dedicated counterparts. My favourite ones were the IRC Mythos Kevlar 1.95 and the Pararacer Smoke/Dart 2.2 (beware kids, this last one is VERY OLD!).

Also I found out sometimes it doesn' matter that much if you put a rear tire in front (Specialized Cannibal, a typical rear tire, was great in the front), or commit other heresies. In the end, the general thread pattern, knob size and spacing, overall tire width, and MOST IMPORTANT, rubber characteristics, count more than the orientation of the thread.

But that's not what Ritchey's "vector analysis" line of tires would try to say to you. By the way, those tires were KING!! (mostly because of their structure and rubber, I'd say).

Well, this is a lot of chatting, but the bottom line would be:

  • In the front, always watch for the direction of the tire;
  • In the rear, you can choose, depending if you traction more (uphill) or if you brake more (downhill);
  • Don't believe in magic too much.
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I actually mount my tires in reverse of the recommended direction sometimes, depending on the tire. Especially in the rear. What I've found is that when a tire has directional tread, it is has more grip in one direction. Thinking in terms of the rear tire, I find most manufacturers will put the rotation direction in the way that would provide better grip when braking. So if you are trying to control a slippery decent, you don't want your back tire locking up easily. However that means there would be less grip for slippery climbs, so the tire would spin-out easier. I usually orient my rear tire whichever way I think will climb better, and compromise my downhill braking if needed, since the front tire can handle braking too, but does nothing on a climb.

Speaking of heltonbiker mentioning old tires, my favorite all around tires are the old Yeti Claws. They shed mud very well, are non-directional, and work front or rear. IRC later made them as and called them "Claw Comp"s. I still have a pair on a bike, but the tires are from like 1998 or so :)

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Not sure this is even still an issue for the original poster, but I didn't see the answer I would have given to his actual question: ["I have a mountain bike tire that has stamped on the side something like: <----------front rear-------------> Which seems like a pretty clear indication that the tire should be oriented in one direction when used in the front, and the opposite when used in the rear. Is that right?"]

No, the tire stamp is pointing in the direction of the front/rear of the bike. Almost assuredly the stamp is actually <---- Rear/Front ------> (rather than Front/Rear) since the industry standard is to stamp this on the right side of the tire. This will put the stamp and colored logos on the same side as the sprocket (not sure if that means anything but that is how I was taught). This is how the manufacturer felt their tire would best be used with air flow and grip, but you can flip it either way depending on your purpose. (I use the logo/direction arrows to mark the tire at the air valve so that when I find a hole in my tube, I can find the thorn easier in the tire as well)

On a side note, if there are 2 direction arrows on the same tire, one says something like "Direction Front" and the other says "Direction Rear" then you would flip the tire depending on if you are using it on the front or rear wheel.

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