just asking as I've cursed a Bontrager ACX and DT 455 for the last hour or so. Gave up and popped it fairly easily onto a Mavic 317. Couldn't even get the **** thing off until I used a large screwdriver and two kitchen knives.

Know how you feel, actually ended up punching myself in the face (don't ask) trying to get a new maxxis crossmark onto a mavic 819.

DT's are known to be a pain more than most.

I was thinking that because the ACX are tubeless ready that maybe made a difference.

Cane Creek rims with Kenda Klimax Lite was a struggle with just thumbs.

Mandatory 2 (polymer, not metal) tyre levers to remove.

I had an extended fight at the weekend fitting some 1.5" Schwalbe City Jets onto X317's. There was some very bad language involved.

brand new michelin DH tyres onto a mavic 729. Hard work and then some.

*cue folk appearing with tales of how they got a BMX tyre onto a 29er rim using only their thumbs*

Had problems with minions on stans flows. Then I got some tips on putting them on and it made such a difference.
Basically when you get to the difficult last 6 inch or so, make sure both beads on the tyre that are already on the rim are seated in the arch (the dip) of the rim. This gives the maximum 'excess'tyre for the last bit.
I was struggling with levers before, but can now do by hand on the same wheel/rim combo with this method.

DT 5.1s. Mine were a nightmare with pretty much any tyre I tried. Never had problems with Mavic or Stans rims though.

Bonty Jones ACX 2.2 onto Mavic 618's is pretty damn tight, same tyres on Flow 355's is still tight but not quite so impossible.

A mate has the bigger ACX's (2.somethings) and they are really baggy and fall off the rims when deflated!

Tightest ever combo I've had was Mavic's with some anti-pinchflat Specialized DH tyres, managed to dent the side of the D521's whilst levering, and the rims were disc only with low walls as well!