Buying products online is an amazing convenience for the average consumer. No more going to multiple places and trying to explain yourself to salespeople. However, it does have one downside: you don’t get to see the product in person. This can be a challenge when buying new wheels for your vehicle because you need to make sure they fit properly.
Fortunately, by correctly taking the proper measurements, you can buy a set of wheels with confidence. While wheel size (the diameter and width) is the most important measurement to know, you’ll also want to calculate the wheel offset and backspacing. If you are unfamiliar with these terms, this guide is here to help. Once you know this information, you’ll be better prepared to buy wheels online.
Defining Wheel Offset and Backspacing
Unless you’re a professional car mechanic or salesperson, there’s a good chance you have never heard of offset and backspacing before. We’re here to help by explaining them to you in everyday terms.
The offset of a wheel is the space between the centerline and the wheel mounting face. The centerline is the exact center of the width of your rims, while the wheel mounting face is the surface that lines up with your axle when the wheel is on your car. The offset of the wheels can be positive or negative, but we’ll get into more detail on that when explaining how to calculate offset.
Next up, we have backspacing. This one is a bit simpler—backspacing is the distance between the wheel mounting face and the back edge of the wheel. While these two measurements might not seem important for buying wheels, their importance will become much more apparent once it comes time to search for wheels online.
How To Calculate Wheel Backspacing
While backspacing is an important factor to know in general, its main purpose is to help you determine the offset. To figure this out, you’ll need a measuring tape and a long, flat edge, such as a level or yardstick.
To figure out the backspacing, you’ll need to lay one of the wheels face down on the ground and place the flat edge across the length of the back end so that it’s over the wheel mounting face. Next, take your tape measure and place the end of it against the wheel mounting face. Use the tape measure to see how far away the base of the straightedge is. This length is the backspacing.
How To Calculate Wheel Offset
Once you know the backspacing measurement, you’ll be able to calculate wheel offset. In order to find this value, you must first determine the centerline of the wheel. Stand the rim upright so you are looking at the section where the tire normally goes. Run your measuring tape across this section to determine the exact center. Then, write that number down—that is the centerline.
From here, you can calculate the wheel’s offset by using the backspacing length. By subtracting the centerline from the backspace, you can determine a wheel’s offset. If the result is a positive number, that means you have a positive offset by the total of your calculation. If the number is negative, then you have a negative offset.
How To Pick the Right Wheels
With the offset value of your vehicle’s wheels, you’re now ready to shop for new wheels online with more confidence! As long as you find a set that’s the same size and offset as your current wheels, there should be no problem with them fitting your car. The best way to ensure this is to buy wheels and accessories that were made for your car’s make and model. If you find the same set of wheels you had on your vehicle previously, you can rest easy, knowing they’ll fit without any issues.
Keep in mind that new wheels don’t have to be an exact match to your current wheels for them to fit. If you want a different design or a larger set of rims, you or want the face to be a bit deeper than before, you can often do so as long as they match certain specifications. In order to determine whether something will fit your vehicle, you’ll need to figure out the size of the wheel wells.
How To Calculate Wheel Well Depth
To determine your vehicle’s wheel well depth, you’ll need your flat edge and measuring tape. Start by holding the flat edge up against the mounting surface of the axle. Then, find the part of the interior wheel well that protrudes out the farthest; this is where the wheel will be the most likely to impact. Once you have determined which part sticks out the most, use your tape measure to determine the distance between that point and your flat edge. You’ll want to add about an inch to that number to ensure clearance. Be sure to do this separately for your front and back wheel wells since they can vary in shape.
You’ll also need to figure out how close your wheels will come to the front edge of your vehicle. With your flat edge in the same position, measure the distance between the front lip of your wheel well and the flat edge. You also want to find the difference between the backspacing of the wheel and the entire width of the wheel that you’re looking at online. If it’s larger than the distance you measured in your wheel well, the new wheels will stick out from the side of your car. You don’t want that!
Also, be sure to pick a set of wheels that aren’t too large in diameter for your vehicle’s wheel wells. One strategy is to is measure the length of the wheel well and pick a set of wheels, including the extra length put on by the tire, that are about an inch shorter than that. Remember, if you still feel unsure, don’t guess! Ask your trusted mechanic or shop to confirm the specifications of the part and its compatibility with your vehicle.