This is mostly caused by tires that are overinflated. When a tire is overinflated, the tire, in essence, bulges out more in the center. The tire then rides mostly on that bulge and that bulge wears faster than the sides of the tire. Keeping your tires properly inflated can help you to avoid center wear.
Lysozyme is abundant in a number of secretions, such as tears, saliva, human milk, and mucus. It is also present in cytoplasmic granules of the macrophages and the polymorphonuclear neutrophils (PMNs). Large amounts of lysozyme can be found in egg white.
If by any chance the examiner will allow you to collect the saliva sample with the swab stick, try to avoid the gums, cheeks and under the tongue. Using a mint is a great way to hide all traces of drugs in the saliva. A cube of ice will help maintain a clean mouth environment and will also help dilute saliva.