to clarify some points , I want to share some of my experiences:
drawbacks for winter tyres
* increases consumption around %5 to %10 depending on avg speed..
* if you are going to make a red/green light drag you are a looser
* brakes/clutch wear/tear rate increase
* you need to purchase 4 ideally, which is not cheap..
* if you are living on a high degree hilly area you have chance only
when its not completely compacted/ice
*they have same speed ratings like summer tyres, but their wear rates
at high speeds are higher as expected but not that quickly
advantages for winter tyres
* forget about 7 celcius limit.. when the weather is below 15 celcius
they work/grip very well and dont wear quickly so that you can use
them at least 2-3 years (or more- I use them at least 4-5 years)
*they can be used whole cold season without installing them back and forth
unlike chains. and they dont damage drive train..
* your suits dont become dirty your hands dont freeze
*unexpected frosts on bridges, valleys dont bite you unless you dont travel
at the speed of sound
*and very important , you drive your car with confidence
* after their last year you can use them also in summer
so if budget permits, I definitely recommend them