View Here : Tire Size Comparison
Tire width is the maximum width of the tire which is usually at the sidewall of an inflated tire. Tread width is the actual width of the tire tread (which is normally less than the tire width). An "LT" after the tire size indicates that the tire is designed for "Light Truck" use.
If you are thinking of changing your car tyre size or are planning on buying a new wheel/tyre combination then you can use the flash tool below for a visual tyre size comparison of your stock wheel and tyre size versus your new wheel and tyre combination.