Baillieu vs Bracks debate re the 10% tolerance

[Full Spectrum]

Originally Posted by flappist

You really have no idea do you?

The circumference of your tyres is dependent on:
Tread wear (new tyres are bigger)
Temperature of the road
Gas pressure in the tyres (which is also temp dependent)
Load carried
Temperture of the rims
Deformation due to rotational vectors (worse with smaller rims)

Your speedometer calculates indirectly from the number of rotations of your wheel per second.
If the wheel is wider because it has expanded you will travel further per rotation therefore your speedo will read lower.

To be 3% out of tollerence you need less than 0.5% increase in radius.
In the case of a standard falcon wheel with is about 65cm to be 3% out is a difference of about 3mm. How deep is your tread?

Of course those are Ford measurements, I am sure you will tell me that Holden measurements are faster and more accurate.......

But with the 3% they also ad 2kp/h on top. So @ 60 kp/h we are looking at 66kp/h that will get you caught.

My wheels are Back 225/60/R15. Front 205/65/R15.
I haven't had a speeding fine even by accident.
Again it's why Speedos are out too allow for wear deterioration of tyres rims conditions etc.

Of course holdens measurements are more accurate and faster why would you think other wise :