My '16 Expert Carbon has 32mm tyres. the 35mm Specialized "Plug & Play" fender set also fits so you might be able to fit 35mm tyres in there (without fenders).

Carbon fibre transmits sounds like nothing else - if your pads are making the noise then they're making the noise irrespective of where you can hear it. There's nothing mechanical in the frame itself. Brake pad squeal is usually because the surface between the rear of the pad and the caliper is not seated our lubed properly.