How about we not turn this into a gleaner bashing thread. Thanks.
If you get the larger size tires, it may reduce the turning radius of the machine. A larger tire tends to come in contact with the returns elevator. Just an FYI, I don't know anything about sizes.
If you're ordering a new machine, I'm sure they'll put on whatever they need to to sell a machine. The only problem I can think of would be that the bolt pattern might be different on the RWA hubs, thus they would require a whole different set of wheels than the 2wd hubs.
18.4 x 26 is on my 2388. My neighbor put 23.1 x26 on his 88. He had to do some small modifications but it looks nice. With these taller tires, the combine will nose dive more than I would like too see. You need to rock your front axel up to the tall position if you want it to run fairly level. The only drawback to this is the machine will be pretty tall for power lines and getting in barns. Many guys are buying the mudhog axels from junkyards or scrap machines. They just want the low profile axel so that they can put 28L x 26 tires on the rear and not have the machine sit so tall.
xc, if you haven't already, cut off the tips of your spreader blades. Measure 1 1/2" in and down then cut diagonally. The new curtains get pushed into the spreaders and shredded. Pretty much every 25xx has this problem.