Bicycle Mechanics - Tires
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View Full Version : Tires
08-19-11, 11:32 AM
Hi, I am an oldie just get back into biking. I purchase some new tires and notice that the front and back are not rotating the same. I seem to remember that tire had a direction of rotation, but do not see that on this tires "Panaracer Crosstowns". Should the tire be reinstalled?
08-19-11, 11:55 AM
An interesting question.
The first thing that I would do would be to examine all of the printing that's molded into the tire sidewall to see if a direction-of-rotation is indicated.
Years ago I read somewhere that, as a general rule, tires should be installed so the triangle shaped tread elements at the top of the tire point toward the front on the front tire and toward the rear on the back tire.
Personally, however, I find the fung shui harmony is disrupted unless the triangle tread elements, both front and rear, point toward the front so that's what I do.
From a functional engineering point of view, I doubt it matters very much if at all.
08-19-11, 12:02 PM
The pointed section should be toward the front when rolling.
Think of it this way, you want the point of the V to hit the ground first and squeeze water out along the channels away from the tire. That's the theory anyway, I doubt it makes much difference on a bike tire
08-19-11, 12:16 PM
I bet it makes no difference and the tire companies want you to think it is.
08-19-11, 03:38 PM
08-19-11, 06:39 PM
Some tires have a directional arrow on the sidewall. And for mountain bike knobby tires there is often a front and rear specific lug pattern and something in the name of the tires will indicate a front or rear. For road tires if there's no directional arrow on the sidewall it makes zero difference how you mount them. But I mount them so the coloured sidewall labels, which are often only on one side, both are on the right side so the bike looks nice in pictures.
Usually the directional arrow it so that the tires ride over the belt overlap a specific way. Yet other tires have no such issues. So likely no bicycle tire needs to obey a rotational direction. Still, if there is an arrow there you may as well obey the rotational direction.
Tread on road bike tires is a case of wishful thinking on the part of the customers and marketing to suit the expectations of the buyers. Our bikes do not go fast enough with the narrow tires we use to even get remotely close to aquaplaning. Many sport motorcycle tires have minimal or no center line tread. And I know from riding such tires on wet track days and races that they stick just fine at speeds considerably higher than anyone can pedal a bicycle on the roads.
08-19-11, 06:39 PM
On the road, it makes no difference. Bike tyres do not hydroplane, so tread patterns squeezing water out from the center have no effect, unlike car tyres where a v-shaped pattern can have some effect.
Off road, v-shaped patterns will tend to give better grip in one direction than the other. As a general rule, the Vs should point towards the front on the front tyre (to give maximum braking traction) and towards the rear on the rear tyre (to give maximum drive traction) when viewed from above.
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