I was looking to upgrade from a ST205-75-14 to a 215-75-14, but I only have about 2 inches of clearance between the top of the tire and the fender with the 215's. I have about 3 inches with the 205's. It is an older Eagle trailer with leaf springs. Fenders are welded to the frame, so no easy way to relocate fenders. I thought about a block between axle and leaf spring, but have read that this is not recommended because of the high torsion loads it puts on the u-bolts when cornering.

Looking for any advice / input.

Going from a 205 to a 215 tire should not decrease your clearance by 1”. It would decrease your clearance by a much smaller amount...see tire manufacturers specs for details.

205/75R14 - 26.1" in diameter, 8.1" wide
215/75R14 - 26.7" in diameter, 8.5" wide
215/70R14 is 25.9" in diameter, 8.5" wide.
That is the general standard measurement for tires, but not all tires are the same. So you have to make sure with each brand as some of the measurements are a little different.

So according to those numbers 0.3 inch closer to the fender when going from the 205 to the 215.

Actually, .02" closer to the fender. 1/2 the difference. Remember, some 215's and other tires are not exactly the same. They may be wider than the standard measurements show. I have seen them .5" wider than the standard measurement. Look at the specs for the specific tire you are interested in to be sure of the width.

Got to www.tiresize.com and put in your current tire. It will give you everything that is close to it. I'm thinking about going to 17's from 14's and I don't have much clearance. I have to go to a 205/55R to keep the diameter and width almost the same to prevent tire rub. I will lose almost 2" in sidewall, but I think it will be ok for my purposes.

26.7” - 26.1” = 0.6” overall diameter increase when going from 205 to 215’s. Half of the 0.6” goes down towards the ground, and the other half goes up towards the bottom of the fender. Hence 0.3” closer to the fender.

Ok. I was talking width (75). My bad. You are correct. I am a couple of whiskeys in the bag tonight, so I can make a mistake.

I have about 1" to 1.5" clearance and my 205's occasionally rub the bottom of the fender. I have leaf springs also.

Here are a few pictures 215 is on the front, and one of the 205 Carlisles is on the rear. Viewed from the side, you see that I could actually use some more backspacing. These are the original wheels and axles that came on the traile . The other side was jacked up in this picture. I probably need to get it settled on all 4 on the ground for a more accurate picture.

How much room is on the backside of the tire (tire to frame)? The wheels look like AR Outlaw II's, maybe? The 215 looks like it has a lot more room than my 205's have, height wise under the fender. Hard to tell about width from the pics, but it looks wider than the 205 by at least the outside rib.

Just by eyeballing your picture, it looks like you have just as much, if not more, vertical clearance between the top of the tire and the bottom of the fender than I did on my last two trailers.