pinched 2 tubes! whats goin on!!

i pinched two tubes today whlist trying to change my friends flat.
i've been riding road for nearly two years now and have never pinched a tube before. my friend's using michelin magnum and its pretty tight to get it on so i used my tyre levers to flick the last bit on, i do the same with my conti GP3000 but have no problems, so whats goin on?
any advice would be good in regards to changing flats particularly with tight fitting tyres.
thanks!

I heard that michelin tires are difficult to install and disasemble. I personally experienced twice now when I replaced my michelin carbon tires. No real advise unfortunately.

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Keith

Vredsteins are even worse.
When you get to the last part of the bead, let all the air out of the tube and then push it towards the opposite side of the tire so it's out of the way.

In five years of riding, I never got a single flat. First trip out with the girlfriend, she gets TWO. Rim strip glue gave out on one spot and the rim was puncturing the tire.

Try a little more or a little less air in the tube, depending on your technique.I generally put just enough air in the tube to give it some shape, not much at all.