Henro, the front tires on your BX are 8" diameter rims, and the BX23S uses a 10" rim. Kubota changed the mounting bolt diameter a smidgen so the new 10" tire will not fit as a replacement for the 8" tire. I learned this when I tried an 8" rim and tire from my old BX22 on my BX23S. All that I can assume is that they also might have changed the gears in the front axle also to match the new diameter of the 10" wheel and tire. Not all tires with the same size markings on the side of the rim are the same rolling diameter. This is why, when I needed new tires, I always looked for the OEM (original equipment manufacturer) tires that are supplied by Kubota.