The present disclosure relates to a lubricating composition usable for lubricating an interface between a tire and a safety support mounted on a wheel rim within said tire, and a mounted assembly for an automobile provided with said lubricating composition. The lubricating composition according to the invention comprises an aqueous or non aqueous lubricating agent, and a polysaccharide intended to thicken said lubricating agent. The lubricating agent comprises glycerine in a mass fraction equal to or greater than about 60% of the lubricating agent and the lubricating agent is present in said composition in a mass fraction of between about 95% and 99%. The invention also relates to the lubrication between the support and the tire when traveling on a flat tire, following a drop in inflation pressure within said tire.