Tires (tyres as British like to write it. Arabic: كاوتش العجل) are one of the most important part of your 4x4's suspension. Tires could make soft ride in hard terrain, can enhance cornering and general handling of the car, can enable dunes driving (with low inflation) or handle rocky puncturing desert marble (high inflation), etc. A broken tire during driving on high speed could be dangerous if you're buying the wrong ones. For this and more, you have to make wise choices of tires everytime you select new ones for your 4x4.