Originally Posted by
operator
Here's a better question. Is a 26 x 1.5 tyre different than 26 x 1 1/2 ? Also is the wheel all the way back into their respective dropouts?
Here is a link, courtesy of Sheldon, which covers almost everything you might want to know about bicycle tire sizing.
http://www.sheldonbrown.com/tire-sizing.html
Much less confusing to use the ISO/ETRTO sizing convention IMO. The old tire sizing conventions are confusing as all get out and can lead to problems with getting the wrong size tires for an oddball rim.
As the OP has discovered different manufacturers tires of the same theoretial size can vary considerably in actual diameter and width, enough to cause problems if clearances are tight. This is one of the reasons that Cateye recommends doing an actual rollout test to determine wheel & tire true circumference for most accurate setup of their cycling computers.
__________________
Gear Hubs Owned: Rohloff disc brake, SRAM iM9 disc brake, SRAM P5 freewheel, Sachs Torpedo 3 speed freewheel, NuVinci CVT, Shimano Alfine SG S-501, Sturmey Archer S5-2 Alloy. Other: 83 Colnago Super Record, Univega Via De Oro
Visit and join the Yahoo Geared Hub Bikes group for support and links.
http://groups.yahoo.com/group/Geared_hub_bikes/