Which Tyre for Roubaix?

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As you may have seen from my other thread I am trying to get maximum comfort, rather than performance.

I wondered if changing the tyres would help, I currently have Mich Pro 3's.

What is the maximum size I can put on the Roubaix? I think it looks like 25?

Plus I pump them up to about 110psi, I am 12st 10Ib how much difference will a wider tyre make?

Thanks

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