Tyres plus skinny rims
I returned the wheels, but I would like to know if it would be possible and safe to squeeze my Marathons onto such narrow rims.
According to the very helpful and definite advice at www.schwalbetires.com/tech_info/tire_dimensions#rim, the retailer is wrong. This says that whilst ETRTO (European Tyre & Rim Technical Organisation) have relaxed their requirements and now permit much wider tyres to be fitted, this permission applies only to rims of 17mm internal width or wider.
That 13mm rim might, perhaps, be strong enough to withstand the higher bursting forces when a 38mm tyre is fitted to a rim that narrow, but the more acute flexing of a relatively wide tyre at the rim edge also has implications for its tendency to chafe at that point. It is unsafe to go against the recommendations of either the rim or the tyre manufacturer.
This was first published in the February / March 2013 edition of Cycle magazine.