terry.sc

The diff is irrelevant, externally the F103 and F104 diffs are identical, with identical widths and identical wheel fitment. The McLaren and Ferrari F104 cars even come with the F103 diff fitted.

If you want to run F103 Ride tyres, they are made to fit Ride rims.
If you want to run F103 Shimizu tyres, they are made to fit F103 normal foam wheels.

Both wheels fit F103 and F104 diffs and if you try to stretch a Shimizu tyre on to an F103 wheel whether it is on an F103 or f104 axle will make no difference as the axle can't change the wheel shape.

Now you can fit the Ride tyre on to an F103 foam wheel, but they are designed to fit into a rubber tyre wheel not sit on a flat surface like the foam wheel. So the tyre sidewall isn't supported unless you make up some rings to go into the step in the tyre.