3 Weeks, 3 Rides, 3 Pinch Flats

Three weeks in a row I've had a pinch flat while out riding; twice at Glentress and then again in the Pentlands on Wednesday. What am I doing wrong, after the first two I had my rear tyre pumped right up to try and solve the problem. Is the tyre shit (WTB Motoraptor)? Is my riding shit? Do I need to slow down and try to take drops and other obstacles slower/smoother? Should I consider a tubeless setup (although I sometimes change to road tyres which could be a pain)?

The rear tyre doesn't seem to be wearing all that well (after about 400 miles mixed on/off road) so I think I'm just going to change it for something else. I'm thinking about a Kenda Nevegal 2.3, hopefully a bigger/better tyre will fix the issue.

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