The majority of the US trucks would need six tyres each. The mileage you could expect from a set is in the thousands, certainly not more than 10,000. High speeds and bad roads would reduce this figure further. At the end of the war the US had exported over 40,000 heavy trucks to France, so if they all needed new tyres at the same time that would be 360,000.
As you can work out they could get through 85,000 tyres very quickly. I am just trying to find out where this photo was taken, but i think it was at the main truck repair/reconstruction depot just South of Paris.
I have just written an article for MMI on this depot (having found a great big bundle of original photos), and hopefully it will come out in the September issue.