I recently had an Automatic RX8 fail the SVA partly because of the gearing ratio.

Gear Ratios (MPH/2000 RPM) for each gear according to the model report should be;
1st - 11mph
2nd - 21mph
3rd - 31mph
4th

 

Well the rolling radius is pretty much fine.

You need to know what they are measuring and where they are measuring from, it could be down to how the mph/kph conversion has been done ??

 

Simon, according to the SVA guys the measurement is taken from their rollers at 2000RPM this is the result...

Model Report/ Reading/ Difference
11/ 14/ 21%
21/ 24/ 13%
31/ 37/ 16%
50/ 55/ 9%

bigger issue? Different gearbox?

 

Your tyre sizes look off, for 16 to 18" wheels.

Have they changed the ratios, or the torque converter slip ratio over the years?

4th (probably direct or lock up) is close, first is a bit over-driven somewhere.

Or does the TC now lock up in each gear, to improve the dreadful consumption figures.

Try teh Rotary Club. But no-one there seems terribly technical, I'll admit.

 

Nick the tyres sizes are fine. I mean they

 

I work it out as 0.5% difference in rolling radius. Which would mean 3% difference in speed due to the tyre sizes.

If you changed tyre sizes, say 225/50/16, then that would be 3% difference in radius, which would be okay, and 18% lower speed, which might get you into range. Please don't take my word for it.

Edited for basic maths.