I've never had any real difficulty fitting tubeless tyres, either gravel, road or MTB...until last night!
I removed a pair of G-ones from my rims and set about fitting some 32mm GP5000s. Damn were they tight. Even using a pair of tyre levers, the tyre would unseat itself somewhere around the rim in its attempts to avoid seating.
In the end I had to resort to a ratchet g-clamp to hold the tyre in place on one side whilst levering the tyre into place on the other side (of the valve hole). Anyway, they're on, but God help me if I get a proper puncture as even if I manage to remove it roadside, I don't think I'll ever get it back on if I'm by myself.
These were fitting to a set of Nextie carbon rims which have previously had Pro-One, G-One and Sector 32 tyres on them...My fingers are still sore this morning
Mine were fine onto a set of Mavic Cosmic Pro SLs, think it could be your rims at play here
Mine went on easily onto a set of dtswiss pr1600 disc wheels.
All the pairs I've fitted (mechanic in LBS) have gone on easy by hand / no levers. How much tape you got on the rims as it could be 'packing' out the rim bed?
1 wrap with about 150mm of overlap.
Mine were fine onto a set of Mavic Cosmic Pro SL
That's interesting, I gave up trying to fit them onto mine. I couldn't get the second bead on, may be I need to have another look. Never had such a difficult rim/tyre combination on either a road or mountain bike.
I find taking them out of the packet and leaving them on the garage floor for a few days helps them regain their shape. Also you can get them on without tyre leavers - use your boot once you've got them on to the last tight bit.
I gave up trying to fit a 25mm tyre to my Parcours wheels, and I couldn't get them onto my Mavic Aksium wheels either.