Good suggestions...I was too discouraged to actually check the second tube when we got back.
On the first flat, I had four other bike club members watching me change the tire, my first ride with the club...just wanted to get it over with...but should have checked for the rim-tire-tube matchup. I'll do that next time.
I'm confused about the snakebite part, because I'd inflated the tire to its maximum 65 lbs when we started the ride. Unless maybe our combined team weight was more than the tire could handle.
I took the bike in for its first checkup today...they're putting on a new Specialized tire that can handle 80 lbs.
Dan