First off, a lesson on copolyester string, per
@PRS's statement above. You're essentially hitting with plastic, which, by its very nature, is going to deform and loose most of its material resilience over time (aka "go dead"). As such, poly is most definitely
not for those who hope they can play the strings for dozens and dozens of hours, without loosing a good portion of playability. That's just not the way the underlying material properties work. Those players are better off switching to a full bed of nylon, polyurethane or natural gut, or some combo of those three.
The above probably comes as no surprise, but you still want to find the longest lasting poly string bed you can. Fair enough. The issue here is that, IMHO, you're approaching it from the wrong angle with a reference tension as high as 60 pounds. Because when you string most any poly at such a tension, you're 1) allowing for more tension available to lose from the get-go and 2) stretching most polys (not all, but most) -- especially something at
brittle as Silver 7 Tour -- well outside of their optimal resilience range, before you even hit a ball. What do both of those things do? They basically kill most of any chance that the string is going to have much of its "magic" to begin with, or retain what little is does have for very long. Instead, you want to play at much lower tension, the lowest you can still control (while also modernizing your technique to take advantage of the increased string travel (snapback) and trampoline). Why go out of your way to do this? Because the string bed will hold way more consistency over time, mainly from 1) having less total tension available to lose and 2) deriving more of its overall playability from the string's
static, innate material properties and less so from those only (or mostly) brought about by just tension itself.
Looking at Silver 7 Tour in particular, as I hinted at above, it's most definitely
not going to play at its optimal best or longest at or anywhere near 60 pounds, not even in most oversized frames, let alone a Pro Staff, especially an 85 (presuming that's what you play with, if your signature is up-to-date). Quite to the contrary, S7T's most optimal range is typically in the low-mid 40's, and that's for most 98-100" racquets. Don't believe me, though. Go search the forum for the dozens of reference points from well-respected members, or better yet, try it for yourself. For a Pro Staff 85, I would think something down in the upper 30's to 40-ish would be plenty of tension, if not still too much. And yes, I know the first response will be, "But there's no way I could control that!" Perhaps not the way you're swinging the racquet now, no, but in time, and perhaps at a lighter strung spec, I'm willing to bet you could, while also unlocking easier depth, spin and launch angle in the process.
So, to recap, sure, moving to the beefiest poly possible will certainly help (older school stiff ones like 4G or Dunlop Explosive Speed, or newer-school, more supple ones that are less tension-effected over time, such as Grapplesnake Tour M8), but ultimately, if you don't start to learn to lower the tension on your setups, you're going to continue coming up
way shorter on playable longevity than you otherwise could, irrespective of whichever poly you put in the racquet.
Hope some of that helps. Any questions, feel free.
