Originally Posted by
D0ugB
The 38 indicates tire width in mm -- the chart that ILTB shows gives you an acceptable range of tire widths that will fit a given rim width -- I believe the origin of that chart is from Mavic originally(not sure looking at it again though)
Source of chart for me was:
http://sheldonbrown.com/tire-sizing.html
Sheldon gave credit to: Georg Boeger at
http://tandem-fahren.de/Technik/Reifentips/index.html
Originally Posted by
cyccommute
Those values are very conservative in my opinion. A Mavic XM719 is a 19mm rim and can take a tire from 1.5" to 2.3". Even that is somewhat conservative, certainly on the low end.
You are correct, the chart is conservative, my commuting bike has 19mm rims and it came new with 622mm (700C) x 47mm tires and I've been using that size for over 6.5 years everyday with no problems.