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How To Measure Your Wheels (Diameter, Width, Offset, and Backspacing)

Fitment Industries Author | | March 13th, 2018 |

  • - Hey guys, what's going on.
    It's Alex from Fitment Industries, and today we're going to be talking to you about, the basics of measuring your wheel. Now I know that sounds like a very simple question to be asked, but car wheel manufacturers do a lot of weird things, and they will mess up your measurements if you don't know how to measure them correctly. So today we're going to be talking about the diameter, width, back spacing and of course offset, so that you know how to measure those things appropriately when it comes down to buying your first set of wheels. So we're going to start off by just measuring the diameter. Now you would assume on a wheel like this that you would just measure from the tip of one point to the bottom of another point.

    So what if you do that, we're going to end up getting 19.5 inches. Well that's not the case at all, it's actually an 18 inch wheel. And that is because you're not going to measure from the outer lip to the outer lip. What you need to do is, you kind of need to guess a little bit on where the actual hoop of the wheel starts. Which if we take a look from the side profile, you're actually going to see it starts right about here. And that's going to give us that 18 inch number. It's going to be the same thing with the width. You would assume that you would measure from the farthest back point to the farthest front point of the wheel which we are going to get 12 inches. So right now we are at a 19 by 12 which sounds pretty cool. But it's not. It's an 18. And it's actually an 18 by 11 And we measure that by going the inside of your bead seat to the inside of the other bead seat, which is going to give us 11 inches wide. So we already got 2 measurements that are different than if we were to measure how any normal person, or maybe first person buying their wheels if their in the garage would measure this stuff. That's where it gets really confusing.

    So the next thing that we're going to go into is something called offset. Now we did do a video where we explained offset in further detail, and if that's something that you're interested in learning specifically about, we'll actually drop a video over here for you to take a look at. But offset is the measure between your center line and where the actual mounting surface of your wheel is. From there you measure the distance between your center line and where your actual mounting hub surface sits. And that distance between those 2 points in millimeters is your offset. So watch that over again if you need to, I know it's a little bit confusing, it can be a little difficult to measure, but it's definitely worth it so you can understand how offset is calculated. No backspacing is something that's actually more commonly used by the older crowd. No offense, sorry guys. And it's used primarily by domestic muscle car owners, they still go off backspacing as a very common way to measure, and it still has it's purpose. You want to measure both if you can. So offset and backspacing are almost the same exact thing right?

    Offset is going to be the difference between the center line and your hub, and where it's actually mounting up to. Whereas backspacing is going to be from your back pad to the outer lip of your wheels. And right here that gives us 6.5 inches of backspacing. So 6.5 inches of backspacing, we're at a plus 8 offset, on an 18 by 11 Cosmos Racing XC206R. These are things that you are going to want to know and understand if you are looking to get extremely tight fitment. A lot of you guys out there that watch our videos are looking for an aggressive fitment so just basing it off of something very conservative and then putting spacers or something like that is just not the way to go. If you want to get it perfect you want to get it done right. So this Alex from Fitment Industries, the next video we're going to talk about is actually measuring it when we have a car on a lift. But let us know if you have any questions as well. Drop a comment below and of course check out our Youtube page and website where we got thousands of wheels and tires. Wheel packages all that sort of stuff. So that is www.fitmentindustries.com That's the sales pitch. But let us know if you guys have any questions. I'm Alex from Fitment Industries we'll see you later. Peace.