Discrepancies in 700c tyre sizing

[Bicycler]

Okay, I know it's best to ignore nominal tyre sizes and go with the ETRTO values but I had always thought that 700x37C was identical to 37-622. However I have noticed that a good many (particularly larger) tyres are marked with two different sizes eg. standard Marathons are available as 37-622 (700 x 35C) and 42-622 (700 x 38C). Are the measurements taken slightly differently and thus do they give additional information about the true size of the tyre?

[Brucey]

they probably also say 28" on them somewhere too, which they are not, not really....

Some of the markings on tyres are there to allow the tyre to be readily identified in certain markets rather than to indicate the true size. It isn't always clear which is which, but the ISO size should be the most accurate, I would have said.

If you want to know the true size of a schwalbe tyre, I think it tells you in their catalogue. IIRC they even explain what size rim they mount it on for measurement purposes.

cheers

[foxyrider]

Generally if you see the two sizes like that the smaller is the carcass size, the larger is the over tread measurement. The larger can be really important if you have limited clearances with mudguards for instance.

The 28" is an over tyre diameter so you might measure it on say a 32c tyre but not on a 23c! its very nominal, 29ers use 700 wheels too but may technically be 60c more or less!