Late reply but here it is anyway.
Wheel rate is what the car actually experiences due to leverage. Just like a car jack, it is much easier (less force) to jack up the car when you have a longer handle. Same principle applies.
lb here is pound-force. Just google xx inch per pound to newton per mm.
2011 E92 M3 DCT
1991 Spec Miata
2008 E92 M3 DCT
2008 E92 M3 6MT
2008 E92 335xi