Dissolve salt in cold water in large container with enough to completely cover the turkey.
Submerge turkey in brine, cover, and refrigerate or store in very cool spot (40 degrees or less) for 6 to 12 hours.
Set wire rack in rimmed baking sheet.
Remove turkey from brine and pat dry, inside and out, with paper towels.
Place turkey on prepared wire rack.
Refrigerate, uncovered, for at least 8 hours or overnight.
Adjust oven rack to lowest position and heat oven to 400 degrees.
Line V-rack with heavy-duty aluminum foil and poke several holes in foil.
Set V-rack in roasting pan and spray foil with vegetable oil spray.
Toss thyme and half of vegetables with 2 tablespoon melted butter in bowl and place inside turkey.
Tie legs together with kitchen twine and tuck wings behind back.
Scatter remaining vegetables in pan.
Pour water over vegetable mixture in pan.
Brush turkey breast with 1 tablespoon melted butter, then place turkey breast side down on V-rack. Brush with remaining 1 tablespoon butter.
Roast turkey for 45 minutes.
Remove pan from oven; baste turkey with juices from pan.
Using 2 large wads of paper towels, turn turkey wing side up.
If liquid in pan has totally evaporated, add another 1/2 cup water.
Return turkey to oven and roast for 15 minutes.
Remove turkey from oven again, baste, and rotate so that other wing side is up; roast for another 15 minutes.
Remove turkey from oven again, baste, and turn it breast side up; roast until breast registers 160 degrees and thighs register 175 degrees, 30 to 45 minutes.
Remove turkey from oven.
Gently tip turkey so that any accumulated juices in cavity run into pan.
Transfer turkey to carving board and let rest, uncovered, for 30 minutes.
Carve turkey and serve.