Good winter tires have softer rubber and do pretty well on ice without the studs. The studs actually reduce traction on wet and dry roads so in all I think the studs aren’t worth it. You should spend the money for the same winter tires on all 4 wheels. If you have ABS brakes mixing winter tires on the back and all season tires on the front is going to be dangerous. 4 non-studded winter tires is the best way to go.