I believe a medical card is needed in all states when driving a combination of vehicles weighing more than 26,001 pounds, a single vehicle weighing more than 26,001 pounds, or when pulling a trailer weighing more than 10,001 pounds with just a few exceptions, even Intrastate. Under those weights there are more exceptions but in most circumstances, it is still required. But also, not all medical conditions will keep you from getting a restricted or limited medical card or even in some cases a full medical card.
Phil
