I have an '01 ford f-150 supercab that have 255/70R16's can I safely put some 265/75R16's on it and what would i have to do.

Should fit on the truck and function ok. Only problem you may have is the speedo and odo will read on the slow side. I believe your truck has an electronic speedo; check with your dealer for the cost of parts and/or programming to correct the error.

Thank you for your reply I am anxoius to Try out my Tires when I get them

yes, your speedometer will read 5.3% slower than you are actually going. You will also accelerate a little get slower and get slightly better highway mileage.