regardless of what tire you run,
check your speedo against a gps.
the best check is to drive 100 miles by the GPS and see what the trip meter reads.
what ever the difference is, that is your percentage of error.
then when you need tires, buy a size that is that percentage different than the ones you are running.
the point is, IF, IF, IF your speedo reads 2 mph faster than actual now,
the larger tires may only make it read 2-3 mph slower than actual.
i wouldn't buy tires just to correct this error, but i would correct it the next time i needed tires.
and i would cut back from driving 9 miles over the limit,
maybe just drive 3 mph over.