wheel offset width difference
 

I currently have the stock wheels with 255 Goodyears -- going to an American Racing AR969 Offroad with 285 tires. This wheel come sin either a zero offset or a negative 12 offset. can anyone tell me how far both of these would extend past my current stock wheels and tires ------- appreciate the feedback

I'd say the easiest way is to convert to backspace. Your OEM rims have 6.25" of backspace. This place gives you the formula to convert. - Wheel Offset to Backspace Calculator | GTSparkplugs

We need to know the wheel width to answer your question.