On 02/02/2019 16:05, Chris Green wrote:
I have bought a new (to me) tractor and to my pleasant surprise the
cab is lower than the ROPS system of my old tractor and thus the new
tractor will fit into my garage if I change the up and over door for
something providing more clearance.

How about this?:

1. Keep the existing doors.
2. Get an air pump.
3. Reduce tyre pressures.
4. Drive in.
5. Pump up tyres again.

And vice versa coming out again. Depending on how often you are parking
the tractor, this may be a lot less work than changing the doors.