Having found out that my axle is actually built for 4400 lbs I want to get over 2200 lbs per wheel and tire or as close to that as possible to have as much loading capacity headroom as possible.

The highest rated 205/75r14 tire I've found is D rated at 2040 lbs so I'd be leaving a significant amount of axle capacity on the table unless I change wheels.  I can get 15x6 5 on 4.5 lug wheels rated up to 2540 lbs. I can get 205/75R15 D rated tires at 2150 lbs so pretty close but still not quite there. Or I can get 225/75R15 D rated tires at 2540 to match the wheels. Looks like I don't need to go to E rated tires to get the capacity I'm looking for which is good because I'm concerned that the ride with the E's would be too stiff.

So, after all that, my question is, does anyone know if the larger tire sizes will fit without rubbing and without a lift kit?

Dimensions:

205/75R14 26.1 dia, 8.1 wide (existing setup)

205/75R15 27.1 dia, 8.1 wide (I'd guess this was OK, I'm only picking up 1/2 inch in dia)

225/75R15 28.3 dia, 8.9 wide (Not so sure about this one)?

My axle is actually designed for a gross axle weight rating of 4400 lbs per Lippert, derated to 3500 by FR for reasons known only to them. 

And yes I know the GVWR and cargo weight limitations and how they were derived. The trailer GVWR calculation is required by NHTSA to be no more than the gross axle weight rating plus the manufacturer's minimum recommended tongue weight, which for my trailer is 285 lbs. Ergo, 3500+285 = 3785 GVWR. Its a made up number driven by a combination of federal regulators and FR's marketing staff trying to show a low tongue weight.  It may or may not represent the actual capacity of the trailer. 

Everyone's actual loaded tongue weight is higher than that, or should be.  In my case it is about 550 lbs so based on my axle capacity I could be at at nearly 5000 lbs trailer GVW without exceeding axle limitations. Other factors like frame member yield strength could govern instead, and I have no intention of loading the trailer that high, but I do like conservative safety factors. 

So, my objective here is to just have the capacities of the wheels and tires match the axle, can't get there with 14 inch AFAIK.  What I'm looking for is any forum knowledge regarding actual tire fitment for the sizes above. 

BTW, I may be making an incorrect statement when I say my trailer doesn't have the axle riser kit. I bought it used this spring so that was just an assumption on my part based on it not being a west coast trailer.  I just pulled a wheel to repack bearings and there is a 3-1/2 inch spacer bolted between the axle and the frame. Is that the riser kit?

As for tires, we run Carlyle ST205/75SR 15, load range D and they are noticeably better than the load range C that they replaced.  Also, we noted a slight improvement in mileage, but this may be more wishful thinking than an objective fact, as I've never done a scientifically valid experiment with all other variables equal except the tires.

Please explain the process and term of "clocked the torsion axle" ?

Ok thank,so your saying it is not something I can change. My only option is to get the risers if I wanted a little more height.   I was surprised when  I was almost scraping just backing into my driveway.   I'm looking into getting some 15 inch tires as well. 

I did order the quick release for the rear stabilizers and will put them on if it ever stops raining.  

they are heavy and well made.  Kinda price for what it is though. 

I went to 15 inch tires and wheels, got these. They fit fine in the wheel wells with the risers. So far I'm pretty happy with them but I don't have many miles on them yet. 2500lb rating on both the tires and wheels. You need the 5 x 4-1/2 inch bolt pattern. 

http://www.easternmarine.com/loadstar-st225-75r-15-radial-tire-aluminum-split-spoke-rim-5-lug-lrd - http://www.easternmarine.com/loadstar-st225-75r-15-radial-tire-aluminum-split-spoke-rim-5-lug-lrd