What is the explanation of motorcycle tire specification parameters?
4 Answers
For example, if the outer tire is marked with specifications 90/90-18-51S, the first 90 indicates a width of 90mm; the "90" after "/" represents the aspect ratio (%), meaning the height is 90% of the width; the "18" after "-" indicates the tire's inner diameter is 18 inches (1 inch = 2.54cm). Some tires do not indicate the aspect ratio, which means the aspect ratio is 100%, i.e., the width equals the height. Below are precautions for tire usage: Pay attention to tire pressure: Tire pressure should not be too high. Due to weather conditions and friction during driving, tire pressure may increase, posing a risk of tire blowout. Clean debris: Remove debris from tire treads. If the treads are clogged with debris, the anti-slip function will be severely reduced, even posing a threat to driving safety. Check front wheel alignment: Front wheel alignment significantly affects tire lifespan, with toe-in and camber being the main factors.
I remember when I first learned to ride a motorcycle, I had no idea what the numbers and symbols on the tires meant. Once, I bought new tires with the wrong specifications, which made the ride unstable and nearly caused me to fall. Motorcycle tire specifications are usually a series of numbers and letters, such as 120/70-17. Here, 120 represents the tread width in millimeters (120mm), the middle number 70 is the aspect ratio percentage indicating the height proportion of the tire, and 17 is the wheel diameter in inches. The letter following these numbers, like H, represents the speed rating, indicating a maximum speed of 210 km/h, which affects high-speed stability. The load index number, such as 68, corresponds to a certain weight capacity in kilograms—exceeding this can cause bulging or blowouts. When selecting tires, it's crucial to match them to your bike model and intended use. I learned my lesson and now always check the manual or consult a mechanic before changing tires. Regularly checking tire pressure and wear is also essential for safe riding—it's not something you can afford to overlook. Especially before riding in the rain, always ensure the tread depth is sufficient to prevent skidding and accidents.
In my over 20 years of auto repair experience, I've frequently seen accidents caused by owners neglecting tire specification parameters. The most common issues are mismatched speed ratings or incorrect aspect ratios. For motorcycle tires with specifications like 140/80-18, the 140mm tread width directly affects handling feel - too wide and steering becomes sluggish. An 80 aspect ratio offers higher comfort but greater sidewall flex. The 18-inch rim diameter must match the original vehicle specs, otherwise rapid tread wear occurs. The letter S indicates a 180km/h speed rating; for frequent highway driving, at least an H rating is recommended. Load index numbers like 71 indicate a 615kg carrying capacity - don't forget to account for rear seat cargo. In terms of construction, radial tires are fuel-efficient and quiet, while cross-ply tires are cheaper and more durable. During maintenance, regularly check tire pressure balance, perform tire rotation every 5,000km or six months, and replace immediately if cracks or bulges appear. Choosing reputable brand tires is more reliable - never compromise safety for cheap alternatives.
As a motorcycle enthusiast, I have a thorough understanding of tire specifications. The key parameters lie in performance matching: a wider tread like 130mm provides stronger grip and better cornering stability; a lower aspect ratio of 60% offers agile handling but poor cushioning, making it unsuitable for long-distance riding. A 17-inch rim diameter is common for street bikes. The speed rating T indicates a maximum limit of 190km/h—higher ratings are safer but don’t push beyond limits. The load index 75 corresponds to over 750kg capacity—match it with your bike’s weight and avoid under-spec options. Check the internal markings for construction—radial (R) tires are lighter and more fuel-efficient than standard fabric-belted ones. Always monitor tire pressure changes due to temperature fluctuations; lower it slightly in summer to prevent over-expansion. Understanding these parameters ensures you choose comfortable, durable tires that enhance your overall riding experience.
