"Andrew" <andrew350902@aol.com> wrote in message
news:bh5icm$lpe$1@news-int.gatech.edu...
> When I compared my speedometer reading with a handheld GPS receiver, I
> found that the speedometer on my '93 Accord read 3% high. Presumably,
> this means that my odometer is 3% high too.

Don't presume! The speedo and odometer are separate instruments. You need
to check the odometer separately. My speedometer is 10% optomistic while my
odometer is almost dead on!

The tires that came with the
> car are 185/70-R14, which seems a little small compared to other cars
> in its class which seem to come with 195's. If I changed to 195's, I
> would cause my speedo to read 5.4% lower that it is now, and 2.4% lower
> than true, so maybe Honda intentionally calibrated the speedometer to
> fall between 185's and 195's so they could have the flexibility to use
> either sized tire with reasobale accuracy.

Few speedos are pessimistic, probably because the manufacturers don't want
to be blamed for speeding tickets. Most modern ones are very close to
correct with the stock tires and wheels.

George