how do you find off set
 

what it says. where do you measrue and any thing else i need to know. i have 2 inwider flared fenders so what off set should i look for?

take a string hand hang it from the edge of your fender measure from the string to the mounting face of the disk or drum.

that measurement is the offset. the distance from the mounting face back is called back spacing and should also be considered as well

To find the offset for your wheels, you need to know how wide the wheel actually is then divide it in half. This will give you absolute half of the rim. This measurement would be 0 offset, the center of the rim.

Now lay the rim face down and take a flat edge across the wheel. Now take the measurement from the flat edge to the hub mounting surface of the wheel. In inches or MM, this will be your total backspacing of the wheel.

Anything more (toward the outside face of the wheel) or less (towards the rear of the rim from the absolute center of the rim will be your offset. Towards the face of the rim from the centerline, will be positive offset... anything towards the rear of the rim from the centerline will be negative offset.