More than narrow tread tires.
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.
New tires are necessary when your tread goes below 30%.
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).
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.
Minimum tread depth for all 4 tires is 2/32"
In the tread there are small 'bars' at the bottom surface about 2-3 mm high, when average tread wear is down to these 'bars' you should get new tires.
Winter tires should be changed out when the tread has been worn down to around 1.5mm to 1.6mm in thickness, after they have been worn down more they are considered worn out. To measure the tread of ones tires one should use a tire gauge which can be bought at websites such as amazon.
For year round tire care and hazard prevention you should be sure that your tires have at least 1/8 inch of tread.
You should replace your vehicles tires approximately every 60,000 miles. Or when the tread on the tire is close to all gone.
Tires should be replaced when the tread wear reaches the level at which your state no longer considers them safe usually 2/32" or when they begin to show signs of irregular tread wear or weather cracking.
On or before your country's legal minimum requirement for tread. If in doubt see out a qualified fitter to check the tread depth for you
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.
It really does not matter how many there are as there are several around the tire. When the tread wear indicators appear flush with the tread you have 1/16" tread left and should look to replace the tires very soon.
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.
the tread is part of the tyre that is supposed to touch the ground
Only aggressive tread new tires whine.
Because they have more tread.
Tires should be checked frequently to look for deflation or wear. A good rule of thumb is to check the tires whenever you change the oil in your car. You should check the pressure and the depth of the tread.
the tyres could blow and you may lose controle of your car
Slow down and make sure your tires have at least 2/32" of tread depth.
The tread on each tire should not be less than 2/32 of an inch deep on each tire. The tires should be free from any defects.
You should get radial tires because if you go to www.mud-throwers.com it lists all of the disadvantages and advantages. So you should spend a little more money on the radial tires.
In the United States, the tread has to be 4/32 (3.17mm) or more on the front tires and 2/32 (1.58mm) or more on the back tires. rear tires can be retreaded but not the front "steer" tires.