There isn't a huge difference in the tension of nylon strings, so don't worry about damaging the instrument. Tension in pounds for various D'Addario string sets:

EJ43 Pro Arte Light Tension Nylon (27.5-42): T = 78.2
EJ45 Pro Arte Normal Tension Nylon (28-43): T = 83.6
EJ46 Pro Arte Hard Tension Nylon (28.5-44): T = 86.9
EJ44 Pro Arte Extra Hard Tension Nylon (29-45): T = 89.7

EJ15 Extra-Light Phosphor Bronze (10-47): T = 135.1
EJ16 Light Phosphor Bronze (12-53): T = 163.2
EJ17 Medium Phosphor Bronze (13-56): T = 188.8
EJ18 Heavy Phosphor Bronze (14-59): T = 217.1

I once bought high tension strings by mistake and didn't even know it when I had them installed. The only reason I ever found out was that the D string broke pretty quickly and I got out the empty package to check the exact description so I could be sure not to buy the same strings again.