We use a build sheet that is much like the form below. This drawing will help you when plotting out your frame and rear width.
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To start:
First: measure inside fender lip to inside fender lip…straight up from the axle centerline. This is usually the widest point of the fender opening.
SECOND: Pick out your wheels and tires. *You will need the tire “section width” which is the total width (bulge to bulge)inflated. *You will also need the mfg’s “width” and “backspace” of the wheels. You will need these dimensions to find the “total backspace”. A measurement that is needed for finding the “rear’s total width”.
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Other things needed:
*Rocker panel “height” (measured in front of the rear tire)
*Outside tire “diameter” or tire height.
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DIMENSIONS*** (for above drawing)
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A….FRAME RAIL WIDTH
B….TOTAL REAR WIDTH (back of wheel to back of wheel) **NOTE: Deduct “rotor” or “drum” thickness to find the “axle to axle” dimension!
C….INSIDE FENDER LIP TO INSIDE LIP (measured over axle centerline)
D….”TOTAL” TRACK WIDTH (outside tire to outside tire)
E….TOTAL BACKSPACE (backspace of wheel plus the bulge of the tire)
F….WIDTH OF WHEEL AND TIRE (inflated)
G….CLEARANCE BETWEEN FENDER LIP AND SIDEWALL OF TIRE
H….CLEARANCE BETWEEN FRAME RAIL AND TIRE SIDEWALL
I….WHEEL WIDTH (measured in between the “inside” lips of the wheels)
J….BACKSPACE OF WHEEL (measured from the back edge of the rim to the back of the wheel where it contacts the axle)
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**ADDED NOTE: When calculating “total wheel width”, add 1/2″ to each side of the wheel’s width. (Example: A 15″ wide wheel is actually 16″ measured at the “outside” lips of the wheel. Use this as a “rule of thumb”.
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Remember!!…the wheel’s “backspace” is also measured from this outside point.
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NOTE: “INSIDE LIP TO INSIDE LIP” mentioned above…on some older cars such as 40s cars…some have tapered outer shapes. You may have to cut the fenders and add a filler to straighten out the fender for adequate tire sidewall clearance
!! IF YOU NEED HELP WITH THE DIMENSIONS, WE WILL BE GLAD TO ASSIST YOU!