My current GoTo bike for local trails is a rigid 29er. I have a Salsa Cromoto fork and my front wheel has the new Easton Arc 30 with a 30mm internal with. I’m currently using a Hans Dampf 2.35 tubeless at about 20 psi. This is all quite nice: the tyre comes up significantly bigger than on the previous Arch EX rim, and I’m pretty happy unless I have to go down something dry, fast, and bumpy. I would like to experiment with an even bigger tyre to push the rigid thing a little further, but I’m not sure whether the Arc will be wide enough to seat a 3 inch tyre securely. I ride XC type trails, and I’m not an aggressive, airborne, big rocks rider. What are your thoughts? Do I have to get a wider rim to go bigger on tyres?

I’ve been running 2.8 Nobby Nic and WTB TBlazer on the rear on 30mm Arc (27.5). No problems on Lakeland rocks etc. What problems are you worried about in particular – burping?

Nice combo, but last time I checked, no 2.8 Nobby Nics were avail in 29er.
And yes, my concern would be the risk of ‘squirm’ and possibly unseating the bead of a 3.0 tyre on a 30mm rim. In the article on the Cotic website about the development of a 27.5+ option for the latest Solaris, Cy and Paul decide on a 35mm WTB Asym rim for 2.8″ Trailblazer. That article suggests to me that a 3 inch tyre on a 30mm rim might be dodgy. However, my riding isn’t nearly as aggressive as those daring young Cotic boys, so I was wondering if there was a 2.7/2.8 ish 29er choice which my survive my more sedate trails and cornering.

We have definitely found that 35mm rims help stability on 3.0″ tyres compared to the 29mm rims we have tried, but it’s not AWFUL on 29mm, you just have to run slightly higher pressure to make the tyre support itself a little more. If you already have a 30mm rim, I’d certainly give it a go.

I’m running 35mm rims (on a solaris) with a 3.0 on the front (no issues at all).

The 2.8 rear (Trailblazer) is way more sensitive to pressures. It can squirm/roll a little on a 35mm so I would think more so on a 30mm. Some of this is probably due to the additional load on the rear but also I think the thinner sidewall of the tyre makes a difference.