It will be less likely to happen with the larger tires. I think the 2.35 BA would be fine on that rim, you might be able to get by with the 2.15 tire. In other threads people have commented that the 2.35 BA tire is more sensitive to road crown versus the 2.0 BA. However, if that hasn’t been an issue for you on the 26x2.35, then I wouldn’t expect it to be on the 29 either. Even with a bigger tire you might want to try lower pressure. Schwalbe claims that their “balloon” tires, such as the BA, roll as well at 2 Bar (~30psi) as a 37mm tire rolls at 4 Bar (~60psi).
A 42mm rim is wider than you really want for a 2" tire, especially at high pressure. This post mentions two different Schwalbe 2.0" tires blowing off the even narrower (38mm) Kris Holm 29" XC Rim at 70 psi.
The ETRTO compatibility chart below indicates that the recommended rim size for a 2.0" (50mm) tire is between 17mm to 27mm inside rim width. (Measurement B in the diagram.) Add 5-7mm to account for the bead hooks/sidewalls and you are looking at a 24mm to 34mm rim. Granted, the ETRTO recommendations will be somewhat conservative, but perhaps that’s because they have to consider tire/rim combinations that will be run at high pressure as well as low. (The chart and diagram are from here.)
Martin
