Welcome!
I know that the dealership can re-correct a speedo up to 35" tires. It'll do about 34, 34.5 really... but mine was done and I'm running 35's and it's just 2 mph off at 97mph. (know from the track). It'll say about 95 and I'm going 97. So that's darn close at lower speeds.
hope this helps!
