I have sold tires for years and can answer this question. There is a huge differnce in the 28 and the 33. It has nothing to do with being a true 10.5 tire. Most 31 and 33 W tires only measure 10.8 inches. There were some 11.2's tires but they were bad new in series like NMCA and KOS as if they ever got wide your run was thrown out.

MT used to issue contact patch measurements for their tires. A 28X10.5 tire you have X amount of square inches of contact patch. A 28X11.5 you have say X+Y for contact patch. A 29X10.5 would give you more than X+Y. An inch of height is worth more than and inch of width. The taller the tire the better off you are with contact patch.

I catch a lot of flack as I now own some 31X13 steam rollers. But, I also raced on 285/60/15 McCreary round track DOT tires back in the day. SO I know a little bit about how to run a small tire.