# What is a Uni-Directional Tire? **URL:** \ **Category:** Factual Questions\ **Created:** [July 14, 2010, 12:01am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608 "2010-07-14T00:01:00Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [July 14, 2010, 12:01am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/1 "2010-07-14T00:01:00Z")
Can someone define a uni-directional tire? How is this different than your garden variety tire? I assume it is somethign about the tread pattern? ---
**Author:** ![Fridgemagnet](https://avatars.discourse-cdn.com/v4/letter/f/22d042/32.png) [@Fridgemagnet](https://boards.straightdope.com/u/Fridgemagnet)\ **Post date:** [July 14, 2010, 12:25am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/2 "2010-07-14T00:25:57Z")
They have an rotationally asymmetric tread pattern, so grip better in one direction. Think of the tread pattern on a tractor rear tyre. For cars the grip direction is (usually) optimised for braking. I’m more familiar with mountain bike tyres, which are mounted in different directions front and rear (there are two helpful rotation direction arrows on the sidewall). The rear is optimised for traction, the front for braking. ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [July 14, 2010, 12:44am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/3 "2010-07-14T00:44:09Z")
Ok, what about other tire terms: Seasonal? All-weather? Touring? Performance? Passenger? Winter? How can one decide what they need? ---
**Author:** ![goldmund](https://avatars.discourse-cdn.com/v4/letter/g/a4c791/32.png) [@goldmund](https://boards.straightdope.com/u/goldmund)\ **Post date:** [July 14, 2010, 1:06am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/4 "2010-07-14T01:06:44Z")
> [@Jinx](#): > > Ok, what about other tire terms: Seasonal? All-weather? Touring? Performance? Passenger? Winter? How can one decide what they need? > **[Tire](https://en.wikipedia.org/wiki/Tire#Vehicle_applications)** > > A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a co... [http://www.tirerack.com/tires/types/tiretype.jsp](http://www.tirerack.com/tires/types/tiretype.jsp) ---
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [July 14, 2010, 1:11am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/5 "2010-07-14T01:11:04Z")
> [@teletype](#): > > [Tire - Wikipedia](http://en.wikipedia.org/wiki/Tire#Vehicle_applications) > > [http://www.tirerack.com/tires/types/tiretype.jsp](http://www.tirerack.com/tires/types/tiretype.jsp) I didn’t think to try Wiki, but on TireRack, I didn’t see where they defined these terms. Musta missed it. ---
**Author:** ![Ionizer](https://avatars.discourse-cdn.com/v4/letter/i/5daacb/32.png) [@Ionizer](https://boards.straightdope.com/u/Ionizer)\ **Post date:** [July 14, 2010, 1:42am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/6 "2010-07-14T01:42:41Z")
Sometimes, the directional aspect has to do with the tire’s ability to shed/push water to the sides of tire, rather than allow tire to hydroplane, or ride up onto the water’s surface, as easily. Think of a ‘V’ pattern - one way pushes water outwards, the other direction will do the opposite. I forget the brand tire, but a son’s friend had this exact thing happen to him on a light truck’s front tires. He told me how he could hydro at less than 30mph, so I looked at tires. WalMart had put 'em on backwards (no surprise there, imho). He had never heard of this, so glad I overheard him that day (!). Typically, the longer-mileage rating a tire has, the less ‘stickiness’ the rubber has (lower grip). ‘Stickier’ tires usually get fewer miles of life, but give great cornering/braking (think dragster tires here). ‘Hard rubber’ can last longer, but will grip less (overall). Tires meant for cold-weather can have compounds added to keep them softer when ‘normal’ tires would become near-brittle. Lots of variance with tires. Arctic-oriented tires would not be ideal for equatorial temperature use, as an extreme example. IIRC, ‘touring’ is kind of meeting in the middle of the extremes, but I have not shopped or compared tires in a while. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [July 14, 2010, 4:01am UTC](https://boards.straightdope.com/t/what-is-a-uni-directional-tire/546608/7 "2010-07-14T04:01:58Z")
> [@Jinx](#): > > I didn’t think to try Wiki, Considering the number of times you’ve been asked to try Wiki before asking simple questions here, I think my head just exploded. This is closed. Colibri General Questions Moderator