| The larger the tire size, the less revolutions per mile. Since the speedo is calibrated with the stock tire size, you need to recalibrate the speedo. When I purchased the 285's on my truck now,they were 4" larger in diameter than the stock tires(245's).When my speedo said I was goin sixty,I was actually going over 65 mph!! So, recalibrate the speedo. |