4.50 -17 is a 120/90/17, or a 130/90/17. I think Mike eventually decided he was going to buy a 130, though I don't know if he actually did. I'd get the 120, if I could find one rated for the load (many 120's are lighter-duty). There are still some tires made with the old inch sizes, though they tend to be the 3.25 3.50 and 4.00 sizes for the most part.