Speedo Correction

[Ira]

Ok, so I jump in the middle and do a little thread whoring, lol. My scantool speed reads dead on my GPS, but at 80MPH, the cluster speedo reads 82. I

Having spent way too much time with 97-02 F-Body clusters on the bench connected to a signal generator I can promise that in general their speedos are not very linear. Some are perfect over the range 20 to 80, but others vary by plus or minus 2 or 3 MPH over that range. If you check it at every 10MPH and it's always high, just drop it by 1.5% or so. FWIW, it will change over 2% over the life of a tire so reading 2MPH high might mean it's time for tires!

Ira

[hquick]

I think I've got it as close as I'm going to get.
3kph at 100kph is OK. You're probably right on the tyre wear issue.
The thing I really don't understand is how the diameter size calculator is different from the 'competition'. Also, the EFILive calculator was out by around 2.5"