What does 99h mean on a tire?
2 Answers
99h indicates that the tire's load index is 775KG, and 'h' is the speed rating, representing a maximum speed of 210 kilometers per hour. The speed rating refers to the highest speed a tire can achieve under specified load and inflation pressure conditions. Most common vehicle models on the market typically use H and V speed ratings, while some high-performance vehicles use W and Y. Tire specifications are data that indicate the geometric parameters and physical performance of a tire. There are three methods for representing tire specifications: A. Metric (m); B. Mixed metric-imperial; C. Imperial. Imperial tire specifications are often represented by a set of numbers, where the first number indicates the tire section width and the second number indicates the rim diameter, both in inches. The most common markings on a tire are, first, the tire brand, followed by the tire specifications, and then the load index and speed rating. The speed rating is the maximum speed limit determined by the tire manufacturer after considering various factors and conducting tests during the design and production process. Exceeding this speed can lead to multiple safety hazards. Generally, all-terrain tires (AT) have lower speed ratings compared to highway tires to account for their performance on unpaved roads. Load index and inflation pressure. These typically indicate the maximum load and corresponding pressure, with the load measured in kilograms and the pressure (tire inflation) measured in kilopascals (kPa). A rubber strip or block on the side of the tire indicates the wear limit. When the tire wear approaches about 4mm from this limit, it's time to consider replacing the tire. The so-called "Three T's" refer to the three markings often found together on the sidewall of a tire: Treadwear (wear resistance index), Traction (traction performance), and Temperature (temperature index). These three indices are additional parameters beyond the conventional size, speed rating, and load index, allowing consumers to make more informed choices about tires, although they are not widely known. In addition to the model, tires also display the following common data: Tire cord material: Represented by Chinese pinyin, such as M for cotton cord, R for rayon cord, N for nylon cord, G for steel cord, and ZG for steel radial cord. Speed rating: Indicates the maximum speed at which the tire can carry a specified load under defined conditions. Letters from A to Z represent certified speed ratings ranging from 4.8 km/h to 300 km/h. Common speed ratings include: Q: 160 km/h; H: 210 km/h; V: 240 km/h; W: 270 km/h; Y: 300 km/h. Rim specification: Indicates the rim size compatible with the tire for practical use, e.g., standard rim 5.00F.
I often help my neighbors with car repairs, and when I see the 99H marking on tires, I can't help but share some knowledge. The number 99 indicates the load capacity—the larger the number, the more weight the tire can bear. For example, 99 corresponds to approximately 775 kilograms. The letter H represents the speed rating, meaning the tire can safely handle speeds up to 210 kilometers per hour. Choosing the wrong tire specifications, especially with incorrect tire pressure (too high or too low) on highways, can increase the risk of a blowout and compromise safety. When driving, I always remind myself to check the tire's production date and wear condition, as good tires ensure better stability, fuel efficiency, and cost savings. Especially before long trips, taking a few minutes to inspect the tire markings can prevent issues on the road.
