The specification and model of the car tires can be directly determined by observing the combination of numbers and letters on the side of the tire. 

The character combination on the side of the tire contains various key pieces of information. Take the common example of "225/60R17 99H" as an example. The first three digits "225" represent the tire's cross-sectional width, measured in millimeters, indicating the width of the part of the tire in contact with the ground. A larger width usually means better grip but may increase fuel consumption; the middle two digits "60" represent the aspect ratio, which is the ratio of the tire's height to its width. A lower aspect ratio offers better handling, while a higher one provides better comfort; the letter "R" indicates a radial tire, which is the commonly used tire type for passenger vehicles and has good wear resistance and a long service life; the number "17" represents the diameter of the wheel hub, measured in inches, and it must be compatible with the wheel hub size for proper installation. The subsequent "99" and "H" are the load index and speed rating, respectively. The load index corresponds to the maximum weight that the tire can bear, while the speed rating indicates the maximum speed that the tire can withstand. Both are crucial for driving safety. 

If you still have difficulties in understanding the tire specifications and models, you can obtain accurate information by consulting professionals, referring to purchase materials or using tire specification calculators. Understanding these parameters can help car owners handle tire selection, usage and maintenance more proficiently. Whether it is for pursuing handling performance, comfort or ensuring driving safety, knowing the tire specifications and models is the crucial first step.