[blerb795]

That doesn't sound exactly correct per the definitions I'm familiar with -- a multi-engine plane with a failure will not safely climb at V1, that's what V2 defines (the speed at which an engine-out aircraft can climb at 200ft/s, with at least 35ft of altitude at the end of the runway). Vr should be when the pilot begins rotation unless an engine is out; I don't believe there's any guidance to wait until V2.