Hi Dave.
Quick dirty correction .... add 10% to what the speedo shows to get you to actual road speed.
From D2 std tyres 235/70*16 to 265/75*16 is a 9.39% increase in diameter.
Not all manufacturers 265/75*16 are the same diameter. They vary.
So 90 = 99 (100!) ;)
See *Alloy Wheel & Tyre Size Calculator
Cheers

