From the Tire Rack:
LT = If a tire ends with "LT," it signifies the tire is either an earlier "Numeric", "Wide Base" or "Flotation" Light Truck size designed to be used on vehicles that are capable of carrying heavy cargo and towing trailers (Numeric sizes), use 16.5-inch diameter rims (Wide Base sizes) or are wider, over sized tires designed to help the vehicle drive on top of loose dirt or sandy surfaces (Flotation sizes). This includes light, medium and heavy duty (typically 1/2-, 3/4 and 1-ton load capacity) pickup trucks and sport utility vehicles. Tires branded with the "LT" at the end of their size designation are also the "little brothers" of 18-wheel tractor-trailer tires and are designed to provide substantial reserve capacity to accept the additional stresses of carrying heavy cargo.
For my purposes, I choose tires that have the LT designation at the end of the size designation.
