Info printed on side of tires explained
Info printed on side of tires explained
There's a lot of useful information on the side of a tire. It shows the brand of the tire, its size, the tire grade, speed rating, the maximum load, maximum inflation, and more. The "P" indicates it is a passenger car tire (as opposed to a truck or trailer tire). The "205" indicates the treadwidth. Treadwidth is measured in millimeters to conform to the U.S. version of a metric tire-sizing system called P-metric. Treadwidth may vary depending on the width of the rim the tire is mounted on. You may loose some treadwidth if a tire is mounted on a narrow rim. Always follow the manufacturer's approved rim width for the specified tire. The "50" tells you the aspect ratio. The aspect ratio is a percentage of the treadwidth that tells the heigth of the tire's sidewall. The height of this tire's sidewall is 50% of 205mm so the sidewall is 102.5mm. The "R" indicates the construction. It's how the plies are constructed within the tire. "R" means radial. If a letter "B" is there instead of the "R" then the tire is a belted bias construction. A letter "D" instead of the "R" means the tire is a diagonal bias construction. The "15" indicates the rim size in inches. This tire is made for a 15" rim. These numbers give you the total tire heigth. This is necessary information when upgrading rim size. The goal for successfully upgrading your rims size is to keep the total tire heigth as close to the one you're replacing. My car came stock with tires measuring 175/65R14. This means the stock tires are 583.1mm tall. First, convert 14 inches to millimeters by multiplying 25.4 by the rims size. 14 x 25.4 = 355.6. Then calculate the sidewall heigth. 175 x 65% or .65 = 113.75. Double the sidewall heigth because you have two sidewalls figured into total tire heigth. 113.75 x 2 = 227.5. Now add the sidewalls and the rims measurements. 355.6 + 227.5 = 583.1. The stock tires are 583.1mm tall. Now comes the tricky part. I wanted 15" rims so that takes up (15 x 25.4 = 381) 381mm of total tire heigth. I'm left with 202.1mm. A 205/50 gives me 205mm of total sidewall heigth which is just 2.9mm taller than the stock tires. That makes the 205/50R15 tires a close match. Close enough to work just fine. For some reason, aftermarket tire shops suggest the 195/50 with a 15" rim as a suggested replacement. The difference is 7.1mm smaller in total tire heigth. I went with a wider treadwidth and less of a difference.Now, let's get back to tire code.The "84" is the load index. Load index is depended upon the maximum PSI listed on the tire. This tire has an industry-standard maximum load of 1,113 lbs. and a maximum PSI (not shown) of 35. Different numbers correspond to different maximum loads. The maximum load is shown in lbs. (pounds) and in kg (kilograms), and maximum pressure in PSI (pounds per square inch) and in kPa (kilopascals). Kilograms and kilopascals are metric units of measurement. The specific values are normally moulded close to the rim in small print. The "V" is the speed rating. This tire has an industry-standard maximum service speed of 149 mph. Tires using an older European system may have the speed rating in the size description like "205/50VR15". Here is a list of speed ratings for tires: Q = 99 mph S = 112 mph T = 118 mph U = 124 mph H = 130 mph V = 149 mph W = 168 mph Y = 186 mph Z = Above 149 mph The speed rating is the maximum service speed of a passenger car tire.The Uniform Tire Quality Grading System or UTQG rates treadwear, traction, and temperature. The tread wear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would wear twice as long on the government test track as one graded 100. Your actual tire mileage depends upon the conditions of their use and may vary due to driving habits, service practices, differences in road characteristics and climate. Just remember that tread wear grades are valid only for comparisons within a manufacturer's product line. They are not valid for comparisons between manufacturers. More than 100 = Better 100 = Baseline Less than 100 = Poorer According to the UTQG system, the tires I purchased from Nitto should wear 3 times as long as a tire from Nitto that received an "baseline" rating at the government test track.The traction grade represents the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. The traction grade is based upon "straight ahead" braking tests, not cornering ability. A = Best B = Intermediate C = Acceptable The tires shown above must have performed well under wet braking conditions to receive a grade "A" rating.The temperature grades represent the tire's resistance to the generation of heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperatures can cause the materials of the tire to degenerate and thus reduce tire life. Excessive temperatures can lead to tire failure. Federal law requires that all tires meet at least the minimal requirements of Grade C. A = Best B = Intermediate C = Acceptable You should always check and maintain your tire pressure to avoid excessive heat which can deteriorate your tires. Proper maintenance of your tires can also increase fuel efficiency.