More than narrow tread tires.
Minimum tread depth for all 4 tires is 2/32"
60% tread wear.
Many tires have tread wear indicator bars molded into the tread. When the tread is worn down to where you can see a solid bar of rubber across the width of the tread, it is time to replace the tire.
I assume you are referring to the tread. High grip will have a more aggressive tread design used in off-road conditions or in deep snow. They are called off-road tires or snow tires. The difference is in the tread design.
While it is good to use tires with the same tread and sizes, it is possible to use tires with different tread patterns, though you should be careful as the performance of the two tires may be different, causing your car to be unbalanced, endangering your passengers.
Because they have more tread.
Only aggressive tread new tires whine.
Slow down and make sure your tires have at least 2/32" of tread depth.
the tyres could blow and you may lose controle of your car
Completer wear of tread surface -(creating an unsafe tire ! )
Some say to change your auto tires every 5000 miles. Other people just check the tread on their tires and when the tread looks worn, they switch their tires.