Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Situational Awareness; Troubleshooting
Ground Event / Encounter Other / Unknown; No Specific Anomaly Occurred Unwanted Situation
General None Reported / Taken
Airport; Environment - Non Weather Related
Upon entering the ramp (Taxiway Delta to Foxtrot) both of us noted that the Foxtrot taxiway centerline on the ramp and perpendicular to the gate centerline seemed too close to the southern edge of the taxiway on the ramp next to the grass. Recommend a site survey be conducted for heavy aircraft arriving/departing San Salvador to better understand how close taxiing on the Taxiway Foxtrot centerline will place the main wheels to the grass and edge of the taxiway. It appeared that taxiing on the Taxiway Foxtrot centerline would put our wheels very close to the grass or in it. We elected to deviate from centerline to keep us away from the edge of the grass and edge of the ramp taxiway.  It is possible that taxiway Foxtrot was measured and painted for B757 and smaller aircraft.  Conduct a site survey of MSLP to determine if the taxiway centerline is measured and painted for larger aircraft like Aircraft X. Publish guidance on the -7 pages describing the need for deviating from taxiway centerline on Taxiway F if it is found to be of sufficient distance from the edge.
Air Carrier First Officer reported the taxi line at MSLP airport is too near the grass area for a large aircraft; creating a safety concern.