here are my 3 mostly used tips for winter steel on the Vedder
T-8 - i use this mostly in late March through until the end of May when the water temps warm up and fish will move farther to attack something
T-11 - my mostly used tip, gets down but not on the bottom in almost every run in the Vedder with slight angle adjustments to your cast
T-14 - I will use this if i cant get down enough in deep runs or with faster water where i need a quicker sink
go into M&Y and have them make you up 12-15 foot tips out of their BULK stock for each sink rate. have them do a different coloured thread for each so you can tell them apart later on. 12 foot tips will be slightly easier to cast especially on shorter spey rods, if your slinging a single hander the 15' tips will actually cast smoother and give you a few more "grains" of weight to shoot the line further. I mostly use 15' tips for swinging but i do also have 10' & 12' tips of each of my heavier tips as well.
you can also utilize an intermediate shooting head or full sink line for swinging flies in the colder months. this will aid in slowing your swing down which slows the fly down which is how winter fish like it. I have an intermediate shooting head from Scientific Anglers and my favourite place to use it is in riffle water because it allows me to cut through the surface water (current is fastest at surface) and slow the swing down. this is usually the type of water fly guys ignore !!
good luck out there