Octane rating - Wikipedia, the free encyclopedia
Specifically:
"Because of the 8 to 10 point difference noted above, this means that the octane in the United States will be about 4 to 5 points lower than the same fuel elsewhere: 87 octane fuel, the "regular" gasoline in the US and Canada, would be 91-92 in Europe."
Locally we use the (R+M)/2 method. Which is the average of RON and MON.
p.s. 95 RON is about 91 here. In Cali (or as I like to say, "Soviet Kalifornia"), the highest available is 91 oxygenated, called "piss water" by most. We get 93-94 here as premium, good for about 4 psi plus of boost over 91. Then we also have E85 (Ethanol, 85%), which is something like 110 octane, and good for 8-10 more psi on my motor.