Going back to the speedometer error, I was interested to read about Civics having a speedo error problem. We have the same problem with our '00 Accord V6 Coupe. It reads 5mph fast at 65 (indicating 70). Unlike other manufacturers, there does not appear to be a way the dealer can adjust the error electronically, though I did not investigate an aftermarket solution. I did, however, do a partial fix with a tire size change. We just replaced the OE Michelin 205/60R16 Energy on at 70K (with 4/32 remaining) with 205/65R16 Primacy. Now we are only about 2 mph off.
I was satisfied with the wear out of the Energy. Could have squeezed another 10K maybe if we lived in a warm, dry climate. They had started to get squirrely in the snow at 4/32. Did not like the Energy in the ride or road noise departments. The car is usually not driven in a spirited fashion (wife's car) so "high performance" wasn't a major criteria but we adjudged the handling an braking performance as adequate but not stellar.
The Primacy is a gigantic improvement in road noise and ride improved noticeably (still fooling with pressures, so it might get better yet). The handling and braking improved noticeably as well. The only downside we noticed initially is that the Primacy seem a little "thumpy" starting off on a cold morning. That seems to have stopped... though it's also getting warmer.
I agree with Crinkles: When possible, I buy five for the rotation reason he stated. More necessary when you do a size change. On our Honda, which has a spacesaver, it's not possible. A fullsized spare will not fit in the well... dangit!