tires sizes ?

helo, My 300 U needs a new tire. 16.9x 28 on rims that look like 14 1/2 or a tad more. This is a real measurement as I have the old tire off. The replacement I have is 13.9 x28 ,I assume on a 12 inch rim. So, the bead will be wider than the tread. How long will this last? I haul some fire wood, plow some snow as needed. I was hopng to get through until something wider floats by. A new one is very expensive, would like to avoid that if possible.

thanks all.,

How you going to put it back together?? The 13.9 by 28 tire, going on the 14.5 rim? Or the 13.9 by 28 tire and the 12 inch rim going on the tractor, replacing both the rim and tire at once, just for the time being?

In my opinion, if the other side your not messing with right now, is the same as the side you are messing with was, the taller the tire ends up, would be better. Which would mean keeping it on the narrower rim, and putting the 13.9 tire and the 12 inch rim on the tractor. Putting that tire on the 14.5 rim would, if anything, lower the tire height which is the opposite of what you'd want. Making the match up to the tire height of the other one, even worse.

Just don't discard the 14.5 rim, and remember to reinstall it when you find another 16.9 by 28 tire. This will also allow you to work on the mounting when the time comes, when you do find the right size, and still have a wheel on the tractor.

How long will it last? Well theoretically, it'll last until that tire is shot. And you did not comment about the condition of the tire in question.
For what it's worth, if it were my project, I'd put it on for the time being, but wouldn't drag my feet and procrastinate finding the right size to put back on. Or put it on and say, hay that is working, I'll just leave it like that. In the future, I'd jump on the first chance I got to come up with a good used one the correct size, and get it put on.

Running two tire sizes is not an end of the world, or a DO NOT DO type of thing. But still kind of a, NOT so good of an idea either. OK for an in a pinch, trying to get by, type of thing. But not for prolonged use, and likely not recommended by the manufacturer.

using same rim, do not have smaller rim, tire only, thanks

That's probably a 14" rim. Rims are measured from the inside of the bead surface to inside of the bead surface.

How long will it last? What condition is the tire in? If it's rotten, not long. 13.9 is an old width they haven't made in I'd estimate 60+ years so you're starting off with an old tire to begin with.

You might have a challenge getting the bead to seat. Use lots of lube.

dont matter what tire u use, as even my oliver 88 's have both size tires and on the same rims. they do not change rims between those tire sizes.

oops my mistake, i was thinking 14.9 not 13.9

It will work. I'd suggest putting a new inner tube in the tire, much easier to get the tire seated correctly on the rim.
TUBELESS ag tires are an absolute PAIN to get properly seated on a rim, even new tires on new rims. BEEN there, fought that battle! Just to pass me off, my new Zero turn mower I bought in 2016, all new tires & wheels, right rear tire leaked down almost flat after I mowed with it the first time. It stays up to pressure for about a month now 7 years later. I bought a cheap Chinese tube to install be too much work for the chances the tube would fix the leak.

I think you'll be OK doing what your wanting to do anyways. Your original post almost made it sound like you also had a choice on the rims also.

Other than looking funny I think you'll be ok. I would try to stay away from the diff lock though.