I am trying to fit a new Pirelli MT21 90/90/21 to my XT660Z's factory front wheel. The old Tourance came off reasonably easily. The replacement MT21 went on fairly easily too, that's when the fun started.

With the valve core removed, I lubed the rim/bead with a soapy solution and proceeded to inflate the tyre, with a 7.5hp 275L compressor, to 50, then 60 then 70 psi, no pop of the bead seating. The tyre appears to be evenly "seated" on the rim, but when I deflated the tyre the bead was still loose, I was able to push it away from the rim with just my thumbs.

I have repeated the procedure several times, using glass cleaner as a lube, with the same result. I put the wheel and tyre in a warm (23*C) room last night, same result this morning. I have tried the ratchet strap method, I have tried bouncing the inflated wheel, and hitting the inflated tyre with a rubber mallet, but it is still not seating.

I am at the end of my tyre fitting skill set, can anyone suggest what might be wrong and how to fix it? I am wary of going past 70psi.

Thanks, RS.