1979-2014 Mustang ARP Differential Cover Bolt Kit These ARP differential cover bolts for 1979-2014 Mustang 7.5 & 8.8 and 1993-1995 Ford Lightning solid rear axles are stronger than the factory bolts and look better too! Designed to securely fasten your differential cover to the rear-end housing and made of stainless steel and feature a polished finish for the ultimate in durability & looks. The best quality fasteners from ARP in the best polished stainless steel finish!
Replace your grime-covered factory differential with our SVE differential cover! Our article and video will give you every step to make this install seamless! more
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The wheel size is the diameter of the wheel, in inches, not counting the tire.
Modern tires in North America have several other measurements associated with their size.
A tire designated as a "225/70R14" denotes a tire with the following dimensions: width of tread: 225 mm; ratio of tire height to width: 70 percent; rim diameter: 14".
Therefore a 185/70R14 has the same rim diameter and aspect ratio, but a smaller overall diameter and narrower tread face than the 225/70R14.
Wheel Width
Wheel Backspacing
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 the backspace.
The photo below shows three wheels with 2", 3", & 4" backspace.
Wheel Bolt Pattern
The bolt pattern or bolt circle is the diameter of an imaginary circle formed by the centers of the wheel lugs. Bolt patterns can be 4, 5, 6, or 8 lug holes. A bolt circle of 4x100 would indicate a 4 lug pattern on a circle with a diameter of 100mm.
The diagram indicates the proper measuring methods. 6 lug wheels are measured like the 4 lug wheels.
Wheel Offset
The offset, measured in millimeters, can be negative or positive, and is the distance from the hub-mounting surface to the rim's true centerline. A positive offset means the hub-mounting surface is closer to the outside edge of the wheel; a negative offset means the hub-mounting surface is closer to the inside edge of the wheel. Offset affects the scrub radius of the steering and it is advisable to stay within the limits allowed by the vehicle manufacturer. If tires are fitted which are significantly wider than those specified by the manufacturer, a compromise may have to be adopted whereby a wheel with less offset is used to prevent the tire rubbing on the suspension.