If you are traveling east or west on I-40 approaching Memphis, I would recommend taking the south leg of the I-240 loop, which runs past Memphis International Airport. I represent many truckers who get ticketed for speeding along the north side of the I-240 loop, which has a much higher police presence. Police will park just over the crest of several small hills running along the north loop or sometimes park up on the ramp area under the bridges to carry out their quotas. There is not a significant mileage difference either way you travel to justify taking the north leg of I-240.