Ha; I did the same thing and figured I may as well have the shoes on hand when I pulled the rotors. At 83K miles I thought sure they would at least be worn enough to warrant replacement but NO! There appears to still be a good 75% of pad left! So I too have an extra set of shoes but I'll probably just keep them or sell them to a PNWX member if anyone needs them.
Guess I should have known; I replaced the fronts at about 65K and they still had a good 40% left. Only did it because I was changing rotors too. Surprises me with all the hills around here and the Seattle stop and go traffic.
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ChuckH
"Every morning when I wake up I know it's not going to get any better 'til I go back to sleep again!" Al Bundy