Do they modify the gearing with the larger tires on the LX models? With the B2650/3350 models they did not change the gearing with the larger tire option, and it resulted in a notable reduction in torque at the wheels (Kubota was upfront about this if you talked to the right person). That is the opposite direction I would want to go in with a tractor if it's used for pulling or pushing, or in a hilly area. I seem to recall someone here on the forum went with larger wheels on a Bxx50 model and had issues mowing on hills, not enough guts. I would be sticking with the standard size wheels and tires if it were me.
They do not, and the over sized tires increase ground speed significantly. If loaded, weight is also significantly increased.
I well remember the thread in question where the B2650 owner's expectations were simply unrealistic.
SDT