I spoke to Bridgestone's regional engineering tech rep on this.
Their reply is that siping alter the tire engineering and there therefor is NOT recommended.
In addition they are in perfect ground to deny your warranty.
For example Bridgestone Tires such as the Potenza's , S0-3, HP-50, Weatherforce etc feature the UNI-T double tread.
Outer side is standard material and as it wears it exposes a second layer of a high wet traction silica compound. So, even worn tires will fair better than brand new ones in wet.
Cutting into the tire prematurely exposes the compound to weatherwing and wear.
Not a good idea...like one person said i would only sipe when there is like 4/32nd left and im driving through a snow pack or monsoon and warranty does not matter.
Knowing me id just save up for my next s et of premium radials
Need Wet Traction? Get a Hydroedge Need Snow Traction? Get a set of Bridgeston Blizzak WS-50.