Ford rims on a Hiace

yes!

but 2cm is not really of any concern; it may make the vehicle a little snakier under heavy braking (!) but many cars have greater variances than 2cm with optional wheels in the same series

Keep in mind that - sometimes - dropping revs wil increase fuel use

Geoff, you're allowed an extra inch (well, 25mm nowadays, sorry) over the regular or factory track, if you fit different wheels to factory standard or factory options.
In your case, there should be little noticeable difference.

The authorities are hot on substantially over-track wheels. Wheels that have more than 25mm over track are not legal without specific inspection.

The reason being that the steering is affected by the wheel centre changing (increasing) its operating radius from the pivot points at the ball joints.
This increased operating radius gives an increase in wheelbase on the side where the front wheel is turning to the front - and a decrease in wheelbase on the side where the front wheel is turning to the rear.
Thus you have introduced increased instability in handling when cornering under load.

The increased operating radius of the wheel centre also increases leverage on the suspension, thus possibly leading to suspension failure (or bending of components at the very least).

The effect only becomes noticeable with substantially increased wheel spacing, and only under adverse steering, braking and handling conditions.

However, the authorities take the view that the vehicle must be stable through the entire range of steering/braking/handling conditions encountered - and have no introduced instability, that might show up when an evasive steering or braking action is undertaken under severe conditions - such as a swerve or hard braking at speed.

Cheers - Ron.

Thanks for the help guys, it seems it will be fine.
My other option would be to fit bigger tyres to the existing 14" wheels.
But there is limited sizes available in light truck tyres.
A friend advised me that car tyres are absolutely illegal on a van, but I rang the licensing authority (wa) and they said its not so, as long as the tyres are rated above the gvm, they are ok.
I am not going to go huge, just add about 7-8 km to the speed.
The speedo isnt accurate anyway, I use a gps to warn me about speed limits.
Thanks again
Geoff