Understanding Wheel Offset, Backspacing and Width – Easy Guide | Truck Accessories Explained

Understanding Wheel Offset, Backspacing and Width – Easy Guide | Truck Accessories Explained


Hey guys, Ken here with 4 Wheel Online and
welcome to Truck Accessories Explained. In this video we’ll be going over what wheel
width, offset and backspacing are, as well as things to take into consideration when
you’re switching from stock wheels. So let’s start with Wheel Width. Although it is exactly what it sounds like,
it can easily be measured incorrectly if you don’t know the right way. Wheel Width is measured from bead lip to bead
lip and is not the actual width of the wheel itself. Now that we have that out of the way we can
move on to the offset, which is related to backspacing but is a separate measurement. So let’s draw a line down the middle of
the wheel… Offset is the distance from the backside of
the mounting surface, to the centerline of the wheel. If the backside of the mounting surface is
exactly in the middle, the wheel has zero offset… But move the mounting surface outward and
you’ll have a positive offset. Do the same thing but move it inward and you’ve
got negative offset. Offset is measured in millimeters from the
centerline. So this wheel has a -51mm offset, while this
wheel has an offset of +45mm. You’ll sometimes see this stated as ET45
depending on the source of info for you wheel. Now that we understand Offset, we can look
at backspacing, which is the distance from the backside of the mounting surface to the
inside lip of the wheel and is generally measured in inches. Like I said earlier, wheel width, offset and
backspacing are all related and important factors to ensure a proper wheel sizing for
your vehicle. Let’s look at a few examples of how the
three relate. We took the stats of three 20 inch tall KMC
XD128 Machete wheels for this example. The first wheel is 9 inches wide. It has an offset of zero and a backspacing
of 5. As we learned earlier, since the offset is
zero the wheel is mounted directly in the center. Now, if you just did the math in your head
you’ll realize that half of 9 inches is 4.5 inches, so how can the backspacing be
5 inches? Easy, the 9 inch wheel width does not include
the lip, but the backspacing does. Next we have another 9 inch wheel, but this
one has an offset of +25. We can see that with this wheel the mounting
surface is pushed outward, therefore the backspacing is increased to 5.98 inches. So more of the wheel sits over the axle. The final wheel is 10 inches wide, but this
one has an offset of -24mm. Being a wider wheel you might expect it to
sit even farther back than the previous two wheels, however that is not the case. The negative offset means the mounting surface
is pushed inward. This wheel has 4.56 inches of backspacing. So less of the wheel sits over the axle. For our next two examples we’ll look at
what happens to a hypothetical 20×10 wheel with a +100 offset and another with a -100
offset. You can see on the -100 offset wheel just
how little backspacing there is, and the exact opposite on the +100. That’s why it is important to consider width,
backspacing, and offset when looking for new wheels. It’s never fun to spend your hard earned
money on a new set of wheels only to find out they rub when turned to full lock or that
they won’t fit over your brakes. Lastly, it should be noted that it’s ideal
to keep the offset as close as possible to the stock wheel, as changing this can affect
the geometry of the suspension and even cause extra stress on the different components. Be sure to take into account your modifications
like lift kits when looking over different wheel options as well, since most are designed
around certain specifications. Now that you know what to look for when buying
new wheels, be sure to check out 4 Wheel Online’s huge selection of wheels and tires right here
*points to the left* And be sure to watch the rest of our Truck Accessories Explained
videos that cover other important wheel topics. Until next time, I’m Ken with 4 Wheel Online.

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  2. Have a question. I have a Jeep Rubicon 4 door 2017 stock and I want to put 35" tires what would the the -offset be, so I do t have to use spacers.?

  3. I am about to get a 1997 F-250. I would eventually like to put new wheels on it. When considering the offset and back space if I decided to put wheel spacers on also will I have to factor that into my new wheel choice. If so how do I go about factoring in the wheel spacer?

  4. I have a 14 silverado lifted 6”, with 17”wheels 0 offset and 33” tires. If i go 20/12/-44 will damage front components like ball joints? Or even 20/10/-24? Anyone!

  5. great informative video. love the way you explained all three and love the diagrams. Now I am ready for some new wheels!

  6. This is really good! Thank You!

    I'm looking at the Promaster city 2018 cargo van for a conversion but want a more aggressive look on this little front wheel drive van. The oem wheels are a tiny 16×6.5 with +52mm offset, tires are 215/55/16 (that's 25.3×8.5) and they look ridiculously small for a box. Specs say the van does support a 15 – 18 inch rims and even 235/40/18 tires (25.4×9.3) Many of the suggested rims are 8 inch wide +35 to +40 offset.

    I'd like a rim and tire to stick out some, fill the wheel well and make a statement. I'm also considering a 2 inch coil spacer in the back as I will adding 800 lbs of furniture and the van but it already looks like its sitting back on tiny recessed tires. I've done mock ups and right tires and rims will transform this van.

    What happens if try to run something with +12mm offset (like 1 – 2 inches out) and/or a tire that measure 27×9.5? I don't mind a vintage more negative 15 inch rim with lots of rubber. I think the back will be fine, but wondering about rubbing on the outer front fender which I have no issue doing some cutting plastic for the right look and better options. I would also be willing to adjust the speedometer. it's my take that going negative on front wheel drive results in rubbing corner of the front plastic fenders and in the middle of the fender skirt. .

    https://drive.google.com/open?id=1xAQ8lCu-FcfsfopWGk2L3LpBg7z_ifhS

    Any suggestions or ideas?

  7. wow, how dumb
    one is in MM and the other in Inches
    Who is the dumb ass that failed to use the same system for both?

    Ok, lets get to my truck, an F-150 (2017)
    It came with 17 in wheels
    I want to change out for 20 in wheels
    what is my Max offset and backspacing I can get away with?

  8. Okay I heard from local 4×4 shop mechanic that the more negative offset produces more strain on steering and lug studs. Positive offset reduces it. What do you think about that?

  9. I’m even further confused..my tire shop want me to install rims with +15 offset on a 35’ tires , will my truck look better with this offset or with the – offset ?

  10. This tells you allot about how a wheel is designed but…..BUT nothing regarding how they look on your vehicle. If you’re going to order wheels online, this info is great for ensuring you get the wheel you ordered, but starting from scratch, this info is worthless in determining which is best for safety and performance or personal preference.
    How about information about negative offset causing the outside of the wheel to travel forward and backward at full turn outside it’s engineered geometry resulting in tire rub.
    Is not zero offset the optimum performance and safety dimension?

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