My suggestion is to put them on now, rubber in front, CT in rear and go regardless of tillage system. Even in the most highly tilled ground, there will be wetter areas of the field that will profit from having the sidewall compaction "chipped in".

And there is no reason to stop to change Curvetine closing wheels in mid planting season! We have many of these working in all sorts of different tillage systems. The Curvetine operates very differently from several of the other "spike" closing wheels on the market. Unfortunately they are often all lumped to gether in people's minds when in fact they use  different principles of action.

That is one of the challenges in closing wheel design: making a closing wheel that "works" and at least doesn't hurt you  across the wide range of tillage conditions we see these days, many times even in the same field.

I think the tillage "purists" are becoming fewer and fewer.

One thing to be aware of however is that a Curvetine has much less surface area in contact with the soil at any given moment than a standard rubber tire. The Curvetine doesn't require anywhere near the amount of spring closing pressure that a rubber tire does.

Running one of each (rubber + CT) you will use less spring pressure than you do with two rubber tires.  since oyu are mostly in worked ground, I would strongly urge you to change the tail piece spring to the lighter JD "half rate" spring available through JD dealer parts counters.  This makes the range much more useable and you will still have plenty of down force for whatever conditions you are likely to run into. This lighter spring is JD part number A-61582.

Regards,

Jim at Dawn