That's very close to a Head TK82S L2 grip size. When I changed the pallets of my Prestiges, I also measured and it came out as this:
A = 31mm
B = 27mm
C = 31mm
that's just an average among all the pallets I've measured. The funny thing is that I got some differences among the pallets, some going up to 28mm in the B measurement. And that was a difference that was easily noticed while playing.
2 Yonex VCore Tour G - Kimony TecniLeather grip / 320g unstrung - strings TBD