Have you tried a tyre seating tool such as this? A friend ended up buying one for a particularly stubborn rim/tyre combo that neither of us could get to work any other way. It worked really well, the only issue is that you have to carry an extra tool in your puncture repair kit.
Cool thanks, I haven’t tried one but I know someone that has something similar , might be worth trying but as you say more concerned about getting it on and then getting caught out , especially as it’s the girlfriends bike !
Have you tried a tyre seating tool such as this? A friend ended up buying one for a particularly stubborn rim/tyre combo that neither of us could get to work any other way. It worked really well, the only issue is that you have to carry an extra tool in your puncture repair kit.