The tires on My 644 are very near their life's end and since Ag lugs in 15" are NLA I am planning on going to 16" rims and tires. My question? Is the backset on the wheel center of newer rims such as the 444/446 the same as early 600 models? And does anyone on here possibly have a good used pair of wheels for sale? I do know there will be some issues as to the clearance between the top of the tire and fender but have figured out what parts I will need to fabricate to make it work and still look good. I know a lot of people go with skid steer tires but this tractor is used as much for tiller and plow work as it is for loader work. any info. would be great Thanks All.