I had a question from a customer about actual widths for some models of the Schwalbe Marathon tires we carry. He is concerned about getting tires that will fit without rubbing on his fenders. I figure others probably have the same questions, so I have compiled a chart showing the actual measurements of some of the tires we carry. I will be updating and adding to the list. If there is a tire you want to know about, and it is not shown, just post it on the comments and I will try to provide actual dimensions for you.
I was going to go into some detail about tire sizing nomenclature but, as usual, the late great Sheldon Brown does a better job than anybody else could. So if you are unsure about what the size markings on your tires mean, check out Sheldon’s page.
All tires will be marked or stamped with the size. 700c and 28″ are two different nomenclatures for the same diameter.
As can be seen a 700c or 28" tire is actually neither. The numbers refer to the diameter of the tire when mounted on a rim and inflated.
The ISO/ERTRO measurement is the first pair of numbers
The ISO/ERTRO number is the most important in determining if a tire will fit on a particular rim. The second number in the pair is the diameter of the rim measured where the tire bead will seat.
This tire has a 622 ERTRO diameter and will fit on any rim with the same diameter measured to the points where the tire bead seats.
So called 29’r tires fit on rims with an ERTRO diameter of 622, but generally have a more voluminous casing so the overall diameter and widths will be greater.
So on to the Tire Width Chart. I measured the width of the inflated tire with a pair of calipers. The “height” is measured from the outer edge of the rim to the road contact surface of the inflated tire.
Measuring width
The "height" measurement
Schwalbe Tire Width Chart
