tires siped?

Siping is the thin little cuts in a tire. They help with traction, and to dissipate heat:

 

This is an example of an un siped tire:

 

Another form of siping:

 

It is commonly done to mudders like the ones chris posted above. It aids in on road traction for that kind of tire.

 

Back ground info:
http://www.google.com/imgres?imgurl=http://www.off-road-outdoors.com/images/siped-tire.jpg.jpg&imgrefurl=http://www.off-road-outdoors.com/tire-siping.html&h=130&w=165&sz=14&tbnid=VVwi8iXqCVhaHM::&tbnh=78&tbnw=99&prev=/images%3Fq%3Dsiped%2Btire%2Bpics&hl=en&usg=__9ten0kZseIBvYxA9GeS5nzA05Sk=&ei=ZiGvSfmVGdCIngehrJG9Bg&sa=X&oi=image_result&resnum=4&ct=image&cd=1



Tire siping can greatly improve off road traction on rocks, ice and hard pack snow. Other advantages include a quieter, smoother ride, and longer tire life.
Siping History - Siping was first discovered during the 1920's by John Sipe who worked in a slaughterhouse plagued with slippery floors.
John came up with the idea to make tiny cuts in the smooth soles of his shoes to give better traction on the slippery floor.

His idea worked so well that he applied for and received a patent for the siping process we are discussing today. Siping For Better Traction - Most tire surfaces are not smooth, but consist of many smaller surfaces know as Tread Blocks. The Tread Blocks get their gripping power not from the smooth tops of the blocks, but from the sharper edges surrounding the blocks.

The many tiny cuts created through the siping process increase the number of gripping edges on the tire. This provides better traction and braking, especially on wet and icy surfaces. Smoother Ride - Most road surfaces consist of a rough texture that gets worse over time. Consequently your tires have to absorb most of the impact. This causes a lot of stress to the tire.

Siping the tires make the tread more flexible, thus creating less road shock, resulting in a smoother ride, less stress on the tire and longer life. Heat Reduction - Heat can be a tire,s worst enemy, causing it to wear faster or even fail. Siping produces results similar to that of a radiator. Sipes allow the tire to warm up to operating temperature faster, but then causes them to run cooler down the road.

Siping doesn’t necessarily reduce friction, the tiny slits allow more airflow over the tire surface resulting in better cooling. A cooler running tire lasts longer!
Machine Siping - Tire siping involves placing tires (new or used) on a specially designed machine found at many tire shops. The siping machine rotates the tires while making small almost invisible cuts in the tread.
Hand Siping - There are several reasonably priced hand tools on the market that allow individuals to do their own siping while some people even make their own siping tools out of utility knifes. Factory Siping - Factory Siping has become quite popular for Mud and Snow and All-Terrain tires. Mud-Terrain and specialty tires are usually not siped at the factory. Factory tire siping is usually quite visible and deep, while aftermarket jobs are shallower and can hardly be seen at first.

 

It pretty much benefits all tires....sans heavy equipment type tires.