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I wondered if someone could explain what "backspace" is when refering to wheels? I have 10" wide wagon wheels on my CJ and I like the look, it gives it a "wider" look. I want to upgrade to an newer aluminum wheel and stick with the 10". What would be the prefered backspacing I should look for and where is it measured from? A friend has 8" wheels on his CJ and used wheel spacers to give it the wider look. I know some of you don't like the spacers, I'm not a big fan either.
I wondered if someone could explain what "backspace" is when refering to wheels? I have 10" wide wagon wheels on my CJ and I like the look, it gives it a "wider" look. I want to upgrade to an newer aluminum wheel and stick with the 10". What would be the prefered backspacing I should look for and where is it measured from? A friend has 8" wheels on his CJ and used wheel spacers to give it the wider look. I know some of you don't like the spacers, I'm not a big fan either.
The easiest way to measure backspace is to lay the wheel face down onto the ground so the backside of the wheel is facing up. Take a straight edge and lay it diagonally across the inboard flange of the wheel. Take a tape measure and measure the distance from where the straight edge contacts the inboard flange to the hub mounting pad of the wheel. This measurement is backspace. The above photo shows three wheels with 2",3", & 4" backspace.
Measuring Wheel Offset
To calculate offset you'll need the following measurements: Wheel backspace, Wheel Width, Wheel Center line (outboard flange to inboard flange measurement / 2)
Subtract: Wheel center line from Wheel backspace to get offset. If backspace is less than the wheel centerline the offset is negative. If backspace is greater than the wheel centerline the offset is positive.
Tip: To convert from inches to mm multiply by 25.4. To convert from mm to inches divide by 25.4.
Backspace to Offset Conversion Chart
The table on the right is q quick reference for finding offset, pick the rim width and follow the row over to the backspace of your wheel.
Determining Vehicle Fitment
Fitting a wheel and tire package is different for each vehicle, but by following these guidelines your chances for success will be much greater. In most cases you'll have to use the physical dimensions of the current wheel/tire package to determine the dimensions of the new wheel/tire package. Items which are potential trouble spots: Tie Rod Ends, A-arms, Brake Calipers, Shocks and Shock Mounts, Inner & Outer Fenders (esp. front tires turned to lock).
In the drawing above, we've made two measurements. Front Side Clearance and Back Side Clearance. These measurements when used with: Tire Section Width, Tire Diameter, Rim Width and Rim Backspace; Help determine if wheel/tire clearance is adequate for the new wheel/tire package you've selected.
Suggestion: Start your search for new wheels by picking the tires first. Get the tire manufacturer's rim width recommendations and physical dimensions for the tires you want. Pay close attention to Section Width and Measured Rims specs., these are important numbers to be used when selecting rims and determining vehicle fitment.
I wondered if someone could explain what "backspace" is when refering to wheels? I have 10" wide wagon wheels on my CJ and I like the look, it gives it a "wider" look. I want to upgrade to an newer aluminum wheel and stick with the 10". What would be the prefered backspacing I should look for and where is it measured from? A friend has 8" wheels on his CJ and used wheel spacers to give it the wider look. I know some of you don't like the spacers, I'm not a big fan either.
Bolt pattern or lug pattern or bolt circle is determined by the number of bolt holes and the bolt circle diameter. Hub Diameter or center bore is the hole at the center of the wheel. Rear spacing or back spacing is the distance from the backside of the wheel mounting pad to the outside of the rim flange. Offset: The distance from the centerline of the wheel to the mounting surface of the wheel. Negative offset: When the back of the bolt pad is closer to the inside of the wheel; when mounting surface is inboard of the rim centerline. Positive offset: When the back of the bolt pad is closer to the street side of the wheel; when the mounting surface is outboard of the rim centerline.
man thats good....also remember that the wider and taller the tire the more chance you have of rubbing the frame and inner fender at full turn.....if you are changing tire height and width you might ought consider doing a mock up to get a sneak peak at what you might get. I have seen guys use sticks and coat hangers to replacate the height and width of a tire and use it to check for fender clearance issues
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