Originally Posted by
jonc123
I looked at the Schwalbe website, the 1.5" Marathon Plus are listed as 40mm wide and the 1 3/4" are 47mm. I would think that would fill out the 55mm fender pretty well. If I could move up to 1 3/4" and get more comfort that would be great. I assume I would have to work a bit harder, but not too much. I could be wrong on all that, have to read up on it. It's some expense and labor to try a different tire and not like it.
If the tires are constructed the same the rolling resistance difference between the 40mm and 47mm versions will be negligible. I don't find tire weight [within a reasonable range] a big deal touring since you are not racing and just trying maintain a pace. The suppleness of the casing is far more important at touring speeds which determines the rolling resistance and that should not be markedly different between the same model of tire in those sizes.