We are talking about several different tires here. The 20 series Bransons take a bigger R4 than the 10 series, and they always have. The 10 series used to use a real short R4 tire. It was a good tire, but with a backhoe on a 10 series with the short R4's, the sub-frame to ground clearance was tight. Around the first of the year Branson switched to a taller R4 for the 10 series. It is not as big as the 20 series, but is a nice size set of tires that look better and give a little more clearance.
Attached is a photo of a 3510 with the larger R4's.