Since the "Replacement Air Springs" thread seemed to end up with severe creep and since the issue didn't seem to come to a consensus here is a little fresh info on the subject.
While visiting Prevost Mira Loma last week I started asking questions about how current airbag replacements didn't seem to perform as well as the old 630126 (Goodyear 1R11-096) "Maywest" springs. The replacement for the 126 is indeed the 630259 (Goodyear 1R11-244). Comparing the specs of the two on Goodyear's tech site shows their specs are identical. There is a difference however in the airsleeve (rubber) part number they use which may have been why the 126 seemed to work better. Coincidental with the discontinuation of the 126 Prevost offered a (surprise) OPTIONAL airbag for entertainer coaches and motor homes. This bag is PN 630151 (Goodyear 1R12-377). This bag is manufactured exclusively for Prevost, consequently Goodyear tech support wasn't willing to divulge its' specs. The bag is a 12" diameter bag however vs 11" for the 259 and you can see from the photo, is about 1" taller than the 259. We can probably assume that when Joe and probably others have ordered new bags from Prevost, they weren't informed these optional bags were available. Hopefully someone will be ordering new front bags in the near future and will be able to report on their performance. Assuming their extended height is 1" higher than the 259 bags and their diameter is 1" greater, an increased volume of about 130cu in is gained with the optional bags. Should make quite a difference