To be honest, for your car, I haven't a clue - may be someone else can help?

BUT I wouldn't worry too much though until you've done this test:-

Get a passenger to count the mile markers on the side of the freeway and compare that with your odometer reading. You'll then get a better idea of the distances you are covering compared with th distances being recorded.

If it is within 10% - which it should be according to the tire info given above - then I wouldn't worry too much as you usually get a correction of 10% or so at speed traps.

You can also use this correction (that you calculate) by adding it to your recorded distance traveled before calculating mpg.