Tires for Boxster?
 

i bought a pre owned porsche boxster, it is almost an year that i have the car now.
i think its time to replace the tires.
i will be driving it in state of missouri.. slight snow..

can any one suggest what kind of tires i need to buy?

are snow tires suitable only when it snows? do we have to switch them with regular tires for summer?

is there any thing like all season tires?

thanks