30 mph, actually, since that is the standard for wind tunnel testing. However, I also rounded every number to a one or five*, so the effect may be the same (I haven't checked, but take your word for it).

*I did some calculations in my head while riding this weekend, and realized that, at least for me, the same approach also works for Crr. Specifically, at my speed/mass, a change in Crr of 0.0005 equates to a difference in power of ~5 W, and hence also a difference in CdA of ~0.005 m^2, a difference in drag of ~0.1 lbs, and/or a difference in time of ~0.5 s/km. Neat how that works out, huh? :-)