When I switched to solid rubber tires because I had found a used set that were almost new at a deal I put them on my 743. They were supposed to be replacement tires for the 12 X 16.5 size tires. I like you was worried they would not fit. Well they worked out great for my needs. You would have to check to see how safe it is for you machine and use but it worked for me without issue. Its makes the space between the tires real slim and the space between the tire and the lift arms real tight but it never rubbed once. I actually found I had better traction with the larger tires.
The only difference I noticed it when grading. Your bucket will not sit flat on the ground because it now is a few inches higher than what the machine was designed to have which is a lower profile tire. So to drag the bucket on the ground you have to tilt it on a downward angle and you are only getting less than half the bottom of the bucket to touch the ground when you do so.
