mtt ET streets

They come with a spec of tread depth measured in 32nd of an inch. You can find out what that spec is, measure what you have left and you'll have more than "everyone has a diff opinion on tread percentage", you'll have a dead nuts on measurement of what's left. Every single tire that carries a DOT approval has to have tread depth maximum and minimum standards. That's why those tires have tread wear indicators.