Interesting Vin !!
I learn something every day.
I know it is vital not to engage 4x4 in my truck on the bitumen even though the front and rears drive at same speed and are the same size.
This is due from turning where the fronts travel further than the rears.
I didn't realise that tractors are behind the 8 ball from the start, in that theire fronts are being driven faster than the rears.
I'd say that using 4x4 in a tractor is therefore only for VERY slippery surfaces??