Deadlift

Today's Crossfit WOD (or Workout Of the Day) was 5x5 max weight of Deadlifts. Here is wikipedia's description of a deadlift:
"The deadlift is a compound movement that works grip strength, and the primary muscles used in the deadlift are the erector spinae, the gluteus maximus, adductor magnus, hamstrings, quadriceps, and the soleus. The remaining muscles are involved in stability control. It is, in a sense, the purest single event test of strength because it is one of the few lifts of dead weight (weight lying on the ground). In most other lifts the weight changes direction or starts in the air and several other athletic skills such as balance, coordination are emphasized. For example, both Olympic weightlifting events require a great deal of athletic skill in addition to strength. In addition, it is commonly believed to be the oldest test of strength, dating back to cultures who competed at lifting the heaviest stones"

I did:
5x 185
5x 205
5x 225
5x 245
5x 255

My one rep max for DL is 290. I used this link to find out that my predicted 5 rep max based on a 1 rep max of 290# is 258# . Not bad!

Question of the day:
Do you use one rep maximums for your strength training? How do you calculate the weight that you use for your strength training? Post your thoughts to the comments...