The prices and advice you are being quoted are ridiculous.
I got 4 Dunlop Sport A2s (205/60/15) mounted and balanced on steel wheels shipped to my door from
www.tirerack.com for $420. That's the top rated performance all season H rated tire (the tires were $55 each) 10 minutes and I was good to go.
Stop trying to shoe-horn a 205/55/16 Z rated tire on your SVT for winter. I used a Yokahama Avid H205/60/16 last year and was dragging my frame and still pulled thru everything.
Buy winter tires for winter (either the above listed all-seasons or the Blizzaks or Michelins) and summer tires for summer.
An H rated tire is no less safe than a Z rated...unless you're driving at a constant 110mph+ in order to overheat them. They're just playing on fear and ignorance. Hell, for winter, you could use S rated tires and stay below 80mph.
Talk to Luke at Tirerack. He'll recommend tires that fir the car...and will do what you want them to do.
