Understanding Tire SizesMaddy Scheinost
Tire Size Explained: Clarifying the Confusion
You’d think finding the right trailer tire sizes and the right ATV tire sizes, or tires for your forklift, ag equipment, lawn & garden equipment and more would be quick and easy, wouldn’t you? The truth is, tire measurements aren’t standard across different types of specialty application equipment, which can make finding the right size tires confusing. Then there’s the facts that some tire sizes are expressed in inches, some in millimeters, and some in both inches and millimeters, and that naming conventions have changed over the years so one tire size may be expressed two ways. That’s why the tire experts at Treadworld want to take some of the mystery out of getting tire size explained. The following information will help you make easy work of choosing the right size tires.
Not surprisingly, the tire size you need is in large part going to be determined by the size of the wheel rim you’ll be installing it on, for any type of equipment. But it’s not really that easy.
Generally, tire sizes are listed on the sidewall. This is true for RubberMaster trailer tires and Master ATV tires and Master UTV tires, for example. But even then, it’s not as easy as knowing the size of your rim and finding that size on the tire’s sidewall, though that’s a good place to start. Rather you need to interpret the numbers you see there.
Trailer Tire Sizes
You’ll find trailer tire sizes are generally broken into main groups of 12 inches and smaller, and 13 inches and larger. The sizes for smaller trailer tires are generally denoted by two numbers, for instance 4.80-12 or 5.70-8. The first number in these examples is the section width of the tire, which is a measurement of the distance from the widest point of a tire’s outer sidewall to the widest point of its inner sidewall, 4.80 inches and 5.70 inches, respectively. The second number is the diameter of the wheel rim the tire mounts on, in these examples 12 inches and 8 inches.
Larger trailer tire sizes are denoted by three numbers, for instance a common tire size is 16.5×6.50-8. It’s a more straightforward process when the measurements, as in this case, are reflected in inches. The 16.5 is the approximate height of the tire, and the last number, 8, indicates the diameter of the wheel rim. The third number, the one in the middle, in this case 6.50, represents the height of the sidewall (measured from wheel rim to top of the tread).
This measurement gets more complicated with tires where the sizes are in denoted by millimeters instead of inches because in that case, the third number is referred to as the aspect ratio, the sidewall height divided by the tire width, expressed as a percentage. The higher the aspect ratio number, the wider the tire’s sidewall, or profile, as it’s sometimes called. So, for tire size ST235/85R16 (the ST indicates it’s a Special Trailer tire that should only be used on trailers, and the R means it’s a radial tire), the 235 indicates the tire has 235 millimeters section width, the 16 tells us the wheel rim diameter is 16 inches, and the aspect ratio is 85%, meaning the height of the sidewall is 85% as tall as the tire is wide.
ATV Tire and UTV Tire Sizes
With ATV and UTV tires sizes, the first number is the overall height of a mounted, inflated tire. The second number is the section width of the tire when inflated and the third number represents the diameter of the wheel rim. So, with an ATV tire sized at 20×10.00-9, the tire is 20 inches high, with a section width of 10 inches, and fits on a 9-inch wheel rim. When there is a dash between the second number and the third number, you’re looking at a bias tire. If, instead of a dash, you see the letter “R”, you’re looking at a radial tire.
Ag Tire Sizes
With agriculture tires, for example the size 11L-14, the 11 means the tire’s section width is 11 inches and the 14 represents a wheel rim diameter of 14 inches. The L indicates this is a low section height tire. When you see an extra number, for instance with wheelbarrow tires size 4.80/4.00, 4.80 is the section width of the tire, 4.00 is the section height of the tire, and 8 represents the wheel rim diameter. If you see the NHS label after the tire size, that notes the tire is not for Highway service.
Forklift Tire Sizes
The most common forklift tires are pneumatic tires or made of solid rubber, with sizes denoted by two numbers. So, in the case of forklift tire size 6.50-10, the 6.50 represents the section width and the 10 represents the diameter of the wheel rim.
Skid Steer Tire Sizes
Skid steer tires are sized similarly to forklift tires, so a tire sized at 10-16.5 has a 10-inch section width and a 16.5-inch wheel rim diameter.
Treadworld Tire Sizes: We’re Here to Help You
When it comes to choosing the right high performance Treadworld tire sizes, we’re here to provide you with any help you need. You can use our 3-Step Tire Match tool on the home page, or you can contact our tire experts for help, either by email or live chat. Our RubberMaster tires and Master tires for both ATVs and UTVs are all manufactured using top quality rubber compounds, before being triple-tested for quality then X-rayed to be sure they’re perfect. Every tire we sell is covered by our Ultimate Advantage Warranty. You can count on us to give you the quality, and the help, you need so you can get the best tires for you.