Our RV tires make our travels possible. But how well do you know your RV tires? Do you know your tires load rating or tread size? What do the markings on your RV tires mean? Well if you don’t know, keep reading because I’m going to help you translate the markings on your RV’s tire and why they’re important to you.
Translating Your Tire’s Markings
RV tires sold in the United States have standardized markings in accordance with the Department of Transportation. These markings provide important information about your RV’s tire. Let’s start translating the information on the tire’s sidewall.
Vehicle Type:
The “ST” (as shown above) means this particle tire is designed to be on a Standard Trailer. Tires can also have “P” for Passenger Vehicle and “LT” for Light Truck. Each type of tire has its own specific characteristics that benefit the type of vehicle they are made for. You should seek advice from your RV manufacturer and/or tire specialist prior to making any changes to the type of tire you place on your RV.
Tread Width:
The “225” (as shown above) tells us this tire’s thread width is 225mm.
Sidewall Height:
The “75” (as shown above) indicates that the tire sidewall height is 75% of the width of the tire’s tread. In this example the sidewall height is 225 x .75 or 168.75mm.
Tire Construction:
The “R” in the example above mean that this tire has a Radial construction. Tires can also have marking of “D” for Diagonal construction and “B” for Bias construction.
Wheel Diameter (measured in inches):
In the example above the “15” on the tire’s sidewall indicates that the wheel diameter is 15in.
Date Manufactured:
The example above shows the date manufactured with a “0417” marking on its sidewall. The first 2 digits represent the week out of the year and the last two digits represent the year. So this tire was manufactured 4th week of 2017. Even tires that don’t display tread wear doesn’t mean they shouldn’t be replaced. The material that makes up a tire will degrade over time depending its maintenance and environmental conditions.
Maximum Pressure Per Square Inch (PSI):
In this example the “80 PSI” is the recommended maximum cold tire pressure, in pounds per square inch, for your tire. The cold tire pressure is the most accurate reading of your tire’s pressure and should be taken before the tire has been driven on or after the tire has been allowed to cool to the ambient temperature. Going above the recommended maximum tire pressure will result in the tire not functioning as designed and can cause damage to the tire. Use a quality calibrated analog or digital tire pressure gauge when taking your tire’s pressure.
Tire Load Index:
The tire load index is the maximum load your tire is designed to support and in the picture above is represented by both “117” and “112” respectively. This tire has two separate load indices because it can be use in dual tire applications. Meaning mounting of two tires in tandem on each side of the axel. In this example the tire can support 2,833 lbs (in a single configuration) and 2,469 lbs (in a tandem configuration).
By multiplying these numbers by the number of tires supporting your RV you will get the total load your tires will support. Our RV has four tires, so the total load our tires can support is 11,332 lbs. (2,833 x 4 = 11,332 lbs). The maximum load rating marked on your tire’s sidewall is for when the tire is inflated to its maximum tire pressure.
Decreasing your tire’s air pressure will reduced its maximum load rating. Use the information on your tire manufacture’s website to find the maximum load for your specific tire at the desired tire pressure.
Speed Rating:
In this example the “N” represents the maximum speed rating for this tire. The maximum speed this tire is rated for is 87mph (miles per hour). Going about your tires speed rating may result in the tire not functioning as designed or cause damage to the tire. Even though our RV tires are rated for 87mph we don’t drive faster than 65mph and sometimes slower if road, environmental, or traffic conditions are not conducive to the safe operation of our vehicle.
Load Range:
The load range for this tire is represent as “E.” This signifies that the tire is equivalent to a 10 ply tire and has a max tire pressure of 80psi. The more plies a tire has, the more rugged the tire is.
Now that you know what the markings on the sidewall of your RV tires mean, you can ensure they are maintained and used properly. These markings are also important when purchasing replacement tires for your RV. So take the time to decipher the marking on your RV’s tires. By the way, this is just one of the topics covered in our YouTube video “RV Tires: Everything You Need to Know.” So go on over to our channel to watch. Check out our YouTube PageYouTube Page for more of our videos.
