I measured and bought the rear covers to fit and then bought the next size up for the fronts. Worked for me.
Jan and Rocky
Volunteers for USFWS. 29 refuges with 9300 hrs ea since 2006. 2004 Allegro 30DA, Workhorse 8.1, Banks, 2012 Jeep Liberty Jet, Blue Ox Aladdin, Brake Buddy Advantage Select, 300 watts solar, 5 Optima group 31 AGM's, 2000watt Ames PSW inverter.