Yes, all vehicle tires have treads on them. Truck tires will usually have larger and deeper treads than regular sedans.
If you're having to put air in your tires frequently then your tires probably need replacing. Also if the tread on the tires is worn down they should be replaced (a symptom of worn tread is the tires squealing on the road for no apparent reason).
Yes. Many people purchase used truck tires. You should always check the tires yourself before you buy them to make sure the tread isn't worn down.
Steal them or some junk yards have tires that will hold air and have some tread on them that are free. Date someone who works for a tire shop.
More than narrow tread tires.
Minimum tread depth for all 4 tires is 2/32"
Depending on the size , tread patterns, type (bias or radial) and taxes, $200.00 to $500.00 and more.
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.
I assume you mean in the tire industry - where (usually) truck tires with good side walls and structural integrity are supplied with a new layer of tread and a new lifespan. This replacement tread is vulcanized to the old core.
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.