I have had ome pretty tight fitting tyres in the past but i still don;t know how people manage to break the plastic one. The ony thing I can think of is that people hold them right at teh far end of the lever from teh tyre. You need to hold the lever right up close. thhe park ones have a nive groove for thumb and finger on the, as a guide.. they seem bomb proof to me... Don'tknow if it's technique or shoddy tools used by others or that I've never encountered my nemesis in tyre form yet but I never seemd to have the issue.... well so far anyway
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