Shadrack - not sure who your question is for - the OP or subsequent posters...
My left rear and right front had a couple of other issues which convinced me that now was a reasonable time to change all 4. 41000 miles isn't too shabby for tyre wear on a big car. (Driving in Canada isn't what you'd call 'spirited')

Peter T
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wel my first comment is ref the op for both outside edges to be swapped to the inside, and my second is just a general comment that if I had worn the inner/ outer edge and done 15k miles or more I'd be happy to replace the set