I don't know of a site, but I did some homework on the subject a while back:
Stock fr:410lb/in---rear:275lb/in
Most manufacturers 2" lift is the same as stock
4" lift fr:560lb/in--rear:stock
6" lift fr:580lb/in--rear:stock
Rancho never gave me a straight answer on spring rates.
Stock fr:410lb/in---rear:275lb/in
Most manufacturers 2" lift is the same as stock
4" lift fr:560lb/in--rear:stock
6" lift fr:580lb/in--rear:stock
Rancho never gave me a straight answer on spring rates.