I have the Honda service manual for the 1987 Civic (US model) and it
confirms what the previous poster said. 175/70R13 82T to be precise.



David L wrote:
>
> According to Tirerack (www.tirerack.com), the original tire size for the '87
> Civic Si hatchback is 175/70-13.
>
> Not really good at math, but there is another website
> (www.miata.net/garage/tirecalc.htm) which gives the calculations you're
> looking for in different size tires. Based on the change to 185/65-15 your
> speedometer would read 8% too slow. When your speedometer reads 60mph
> you're actually traveling at 64.8mph.
>
> If you want to change to a 15" tire, get the 195/50-15. That would only
> make your speedometer read .1% too slow, so if your speedometer reads 60mph
> you're actually traveling at 60.1mph. You can also opt for 185/60-14 which
> would read .4% too slow so when your speedometer reads 60mph you're actually
> traveling at 60.3mph. All of the above info was gathered from the two
> websites quoted.
>
> It'll probably be more trouble that what it's worth to try and change the
> speedo. Upgrade to the appropriate corresponding tire size instead.
>
> Hope this helps,
> -Dave
>
> "Tina Venne" <TinaVenne@comcast.net> wrote in message
> news:f959jv0rgaa731mf5avckpqu4ac1c780ko@4ax.com...
> > Can anyone tell me what the original size tires were from the factory
> > on the 1987 Civic Si?
> >
> > If someone is good at math, can you tell me what the speed difference
> > would be, as indicated on the speedometer, between this stock size and
> > the currently installed P185-65-R15 at, say, 60mph?
> >
> > Also, where can one obtain the driven gear (or whatever it is called)
> > that would correct the speedometer for the above current tire size?
> >
> > Thanks a bunch.