Good one, Granpa! They left 'em off because the 1800's suspension doesn't use air for adjustment like the 1200 and 1500 did. Filling tires was just a bonus; the main reason was for the suspension.granpa in Cincy said:The 1800 doesn't have an onboard air compressor. The 1500's did.
They took 'em off the 1800 to save weight.