98 civic LX 270000kms 5spd 4dr

Last few days when I get home, I smell burning rubber, and have tracked it
down to the passenger rear tire.

The tire has been making the 'thump thump thump' noise for a while, so I
swapped it out for another tire I have sitting around.  Took the car for a
test drive, went 2 miles at about 140kph.  Got back and the smell was still
there!

What could be causing this?  The tire I pulled off does not appear to be
badly worn.  It is well above the wear bars, rolls without falling over, and
is not cupped.

I'm thinking alignment....  ideas?

t