Trailer tires?

So I went out to look at the tires on the trailer the other day. Its time for some new tires, I have a couple that are starting to rot. My question is I have a new spair that is a 205/75R14 and a replacement from a blow out a year or so ago that is the same tire. The other three tires are 215/75R14. Does it matter what size tires I get. I want to just to buy to more 205/75R14s and then have 4 good tires and keep the best of the old three for a spare. Is there any reason I should worry about getting the larger tire? It would save me some cash only buying 2 tires vs buying 4.

bigger tire typically means more load capacity, which means a cooler running tire. going from the 205's to 225's on my trailer gave me a 2,000lb margin over what I had before..

Yeah I see your point but my trailer is rated for 6000 lbs. with the 205's there rating is 1760 each tire. That puts me at 7040 lbs of handling for the tires plus the weight of the trailer its self and the jeep. Don't get me wrong if I find the money for the 4 215's vs just getting 2 205's I will be spending the money for the upgrade. My point is, is it a bad idea to cut the margin that close are should I just bite the bullet and buy the bigger tires?