I'm looking for a little reality check on my roll out measurement. I'm using a Cateye Strada wireless computer. Today I went on a 9 mile ride and compared the Strada's distance to a Cyclemeter app on my iPhone. The Cateye came out about .25 mile longer than the GPS app.

My bike has Bontrager 700 x 35c tires. According to the Cateye circumference table this works out to 2168mm which is how I set the computer. However, I did a roll-out measurement after my ride and it came out to about 2180mm which is closer to 700 x 38. Is it possible that I have a tire marked at 700 x 35c that has a 218cm circumference?