cant see why not,try asking some one like Jules at track car solutions.hewas probily the first person to supply and fit nitrons and done loads posibly rear spring rating different? but only guessing.
Thats interesting, may have found some nitrons on a cerb fairly cheap and relitivly new, however if im having to change spring rates it might not be worth it.
To be fair if the nitrons are fairly new, and fairly cheap it would be silly not to buy them anyway they won't need reconditioning if they're newish .. for which read less than say 24000miles in real terms.