The factory fit conti's are 84 load rated.Is this the lowest load rating we can use? I was looking at some 16" winter Goodyears (winter wheels),but they are 83 rated.

I thought the XL part was the most important part?  That might influence the load rating, I guess.

 

XL winters aren't hard to find, just not much choice...

XL just increases the load rating value a couple higher than the normal tyre, they don't need to be XL, just the correct minimum load rating.