Tires & Wheels
Published April 3, 2020
Tire Sizes Explained
Ever wondered what all the letters and numbers on your trailer tire mean? Let’s break it down. All our of our tires are labelled similar to this: ST205/75R15. Here’s what the letters and numbers stand for:
– ST (ex: ST205/75R15): Stands for “Special Trailer”. Tires with this prefix should only be used on trailers, boats, or cars.
– 205 (ex: ST205/75R15): The first 3 digit number after the prefix is the measurement of the width of the tire in millimeters. Most of our tires are either 205, 215, 225, or 235.
– 75 (ex: ST205/75R15): The number following the slash is a measurement of the aspect ratio of the tire profile. So, 75 means that in this tire the sidewall distance (measured from the top of the wheel trim to the outside of the tread) is 75% of the tire section width. A higher number will indicate a taller tire with a higher sidewall, while a lower number will be for a lower profile tire with a shorter sidewall. Our tires are either 75 or 80.
– R15 (ex: ST205/75R15): The last number represents the wheel diameter in inches that the tire should be matched to. Most of our trailer tires are 15, 16, or 17.5 inches.
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Which Tire Will My Trailer Come With?
Since we specialize in customizable trailers and our website configurator lets you build and configure any model you choose, all of our trailers feature multiple options for upgrading to different compatible tires. For even extra customizability, consider a black or two tone aluminum WHEEL COLOR.
There’s a few simple guidelines involved in understanding which trailers come standard with which size of tire:
In general, all trailers rated 14K and up will come standard with 10 ply (235/80R16 Radial) and up tires, and smaller trailers rated lower than 14K will come with 6 or 8 ply tires standard. Our HD 215/75R17.5 TIRE UPGRADE is included with most trailers that offer an 18K or 20K GVWR UPGRADE package. All 215/75R17.5 tires also include premium VALCRUM HUBCAPS for a stronger, more durable threaded hubcap.