It often depended on where and when one was traveling. England has some of the best surviving records of trade in medieval Europe, but these still offer little direct information for the outfitting of overland trade. The view of medieval roads has traditionally been pretty negative but more recent research indicates that the roads were probably better maintained than previously thought, but many were still mostly packed earth and could become notoriously muddy in winter time when the weather in much of Europe turned wet. Overland travelers would face many obstacles but many of these eased over time as more infrastructure was constructed. Crucial to medieval trade and transportation was the construction of bridges which made crossing the many rivers that studded the continent much easier. In addition to roads and bridges, inns and hostels were important to overland travel. By the middle of the 13th century most of Europe was fairly densely populated and there were few true wildernesses left in the lands of Western Europe so traders would not need to prepare much in the way of supplies for their own consumption and could expect to have the opportunity to stop in a town when they needed food or sleep. Depending on the political stability of the region through which they were passing traders would need to prepare for the potential of robbers or bandits, but in most regions where a strong king or lord reigned, crime would not be major concern, however, if an area was politically unstable, which many were, a trader might have to employ guards to protect their goods.

Overland trade would have largely been conducted with carts or packhorses. Two and four wheeled carts pulled originally by oxen and then later by horses were common in high and late medieval England and were probable the primary form of transport. But in areas where roads were particularly difficult, in mountains for instance, packhorses would probably have been used despite their lower carrying capacity. Carts ran on narrow wooden wheels that were susceptible to mud and not particularly efficient so movement was relatively slow, probably in the realm of ten to twelve miles a day if conditions were fairly dry, but even slower in wet weather. There is little indication that medieval roads were paved outside the immediate vicinity of towns but more research needs to be done on road materials and maintenance before it can be said definitively what medieval roads were like.

If you want to learn more about the mechanics of medieval transport I would recommend these works:

English Inland Trade 1430-1540: Southampton and Its Region. Michael Hicks, ed. Oxford: Oxbow Books, 2015.

John Langdon. Horses, Oxen and Technological Innovation: The Use of Draught Animals in English Farming, 1066-1500. Cambridge: University Press, 1986.

Eljas Oksanen "Trade and travel in England during the long twelfth century" in Anglo-Norman Studies, XXXVII: Proceedings of the Battle Conference. Ed. Houts, Elisabeth van. Woodbridge, Suffolk : Boydell & Brewer, 2015. pp. 181-204.