Wheel offsets
 

Looking to fit some different wheels to my 20y.o Mardave Cobra/Meteor buggy.
I can soon change the front axles to the more common 5mm diameter and the rears to a Tamiya
type.

I need to know how to work out the wheel offset though.

It seems that no-one makes alternativewheels for these old buggies,
so I'm eye-ing up RC10/Losi type dish/5 spokes but need to get them
with the correct offset for the rear and bearing-in-wheel type for the fronts.

Anyone know what the formula/method is for working out/measuring wheel offset is please?

Mark