I talked to the Goodyear guy about mine. Put over 10,000 miles on my Marathons this year (about 28,000 miles since new 3 years ago) and the front ones are showing an "over pressure" wear pattern (center wear greater than edges). The rears are straight across wear (normal). This means that the front axle is carrying slightly less load than the rear axle.
He suggested "if I wanted" to rotate front to back and keep the tires on the same side. I decided not to rotate them and just put a new set of 4 on at the 40,000 mile point.
Lou and Laura with Bella - German Short Hair Pointer
2008 GMC Sierra 2500HD Crewcab SB Allison Duramax
2010 Flagstaff 8526RLWS - Superglide 3300
HAM CALLSIGN - KC3FFW