I am considering putting some wider tires on my 2018 Cannondale Quick Disc 2 for some gravel and very light trail use. The stock tires are 700 x 30c. the rims have an internal width of 15mm. There is ample clearance between the chain stays and fork. I am considering 700 x 32c and maybe even 700 x 35c tires. I feel confident that the 32c would fit OK, but would 35c tires be too wide and cause any damage to the rims?
I’ve used 35mm tyres on DT Swiss RR415 rims with a mere 14mm internal width. The main problem was that at low pressures (<3bar) the tyre tended to “collapse” sideways in sharp turns. Very high pressures (like >5bar) could maybe cause damage to the rims, but at least with disc brakes you are not wearing down the rim walls over time.
So I’d say go ahead, but for the best performance you’d really need slightly wider rims.