I also like this one so you can set the gears:
http://gs.tolan-hoechst.com/tirecalc.htm

Although, personally, I crack out a spreadsheet and generate the formulas
myself (not hard at all if you think for a bit).
but you can't adjust the speedo, you can swap the speedo, with one from an
EX, for example, which might have stock tires close to that size.
Since most speedos under-read to begin with by about 5%, maybe more, (my 94
CX was closer to 10%) you may have increased the accuracy of your speedo,
but that also means, that if you used to cruise down a 35MPH road at 45, but
were really only going 41, a cop may not care, but now that you are actually
going 45, you could get pulled over.


"Falco" <pepeduran533@hotmail.com> wrote in message
news:Ra4Za.24262$bo1.16121@news-server.bigpond.net.au...
> Go here workout the difference and draw some lines on your speedo.
> http://www.miata.net/garage/tirecalc.html
>
>
> pepeduran533@hotmail.com
>
> "Mista Bone" <MistaB0ne@cinci.rr.com> wrote in message
news:JE1Za.49394$hc.46797@fe3.columbus.rr.com...
> > speedo gear cannot be adjusted or replaced with a different size.
> >
> > --
> > Charles Tague
> > 93 Honda Civic DX HB
> > 1.6L SOHC VTEC 14.85 @ 89 mph,1.98 60 ft.
> > With ZEX 85 hp ZEX 13.09 @ 103 mph, 1.81 60ft.
> > 86 Pontiac Trans Am
> > 225/50/15 GForce Drag Radials
> > 305 peanut cammed 15.29 @ 88 mph
> > http://home.cinci.rr.com/mistab0ne/
> > "Tina Venne" <TinaVenne@comcast.net> wrote in message
> > news:8a59jvo8rhued647kduden8ocrs4m6fsbv@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?