If y'all don't mind, I'll revive this yet again.... ICE T tadpole trike. Came with Schwalbe Marathon 20x1.5 tires on 406 size rims. Bought NEW Marathon GG tires in 20x1.75 AND the correct Schwalbe tubes.

Tires won't seat. Tried different tires on different rims. Tried different tubes - old/new. Put the old tire back on - worked perfectly... Here's what's been recommended in here (I've tried them ALL for the last 24 hours):

-- deflating the air pressure to about 5 lbs and "pulling" the bead outward with my fingers.
-- pumping in 10-15% higher pressure than the tire's max rated pressure - in THEORY, the tire is good for 8.5 BAR, which is 116 p.s.i, although the rating on the side is 70 psi.
-- deflating the tire and wetting the bead with soapy water. Inflate. Repeat a half dozen times. nothing.
-- deflating the tire and putting talcum powder around the bead AND on the tube. nada.
-- I checked the rim strip on all 3 rims - they're in the center, not going up either side.
-- Checked the tire bead very carefully - no nubs, globs, chunks, oddities, rough spots, or anything on the tires.
-- Put in just a little air pressure (~10psi) and then went around the tire pressing the tire bead in away from the rim to try to get it to seat better. A "rolling" action may also help where you start to roll the tire off the rim. Did this repeatedly. Made no difference when filling the tire.
-- Checked ISO numbers on ALL the tires and the rim. Everything matches.
-- Checked all THREE tires - no kinks ANYWHERE on the brand new tires.
-- Tried multiple tires on multiple rims with different tubes of different sizes to see if that mattered. Nope.
-- I made some soapy water that was not more than 10% water. Made no difference.
-- Use more air pressure. Keep going until the bead pops into place. A little soapy water won't hurt either.
Don't think I have the guts! Tires say 70 psi. I ran them to 105 then set them aside to see if they'l seat. I'm not sure I want to get anywhere near one of these at 2X or 3X the recommended pressure.

-- down the road to the next SAG stop where the driver whipped out a Park Tool "Tire Seater". Worked like a charm..
Went to the LBS. They had one of those tools. Air in. Grab with tool. Twist. Nope. Let air out. Do same thing. Repeat several times. Swear. Let air out. Wet with soapy water. Repeat previous. Tell me the rims ICE uses aren't very good. Suggest I ride the bike and maybe the tires will seat.

At this point, ONE tire seated, one has a low spot on one side, the third has a low spot o both sides. Finally, I wet 'em, mounted 'em, plugged 'em into the compressor, and filled them to 100+ PSI and set them aside. I'll later if they're better...

WHAT A PITA! Anyone have any other ideas?