CarloM

@tony2v yikes, that is cutting it really close! Thank you for taking the time to post those pics, very informative.

I just bought digital calipers and found something really interesting.

Here's is the Cervelo S3 with ENVE SES 5.6 Disc (19mm internal width) and Continental Grand Sport Race 23c


Here's my Giant TCR with Black Inc Thirties (17.5mm internal width) with Mavic Yksion Pro UST 25c


So the 23c on the ENVEs measure out at 25.73mm, which is nearly 3mm wider than listed, while the 25c on the Black Incs only measure1.4mm (26.4) wider than expected.

I'm afraid if I order 25c tires for the ENVE it will significantly exceed what the 25c Mavics on the BIs come in at.

However, a friend suggested to me that the Conti 5K TL (which would be my TL tire of choice) measure close to spec. Sure enough, I just measured my backup wheels/tires combo: 28c Conti 5K TL on Bontrager Aeolus Pro 3 wheels, which according to Trek's site has a 19.5mm internal width (so actually 0.5mm wider than the ENVEs) and here's what they measure at:

So the Conti 5K TLs do only 0.81mm wider than list, and on a 19.5 internal width rim, no less.

I think I may risk ordering 25c Conti 5Ks and hope they stay close to what the 25c on the Black Incs measure. Since that's less than a mm wider than what I have right now, there should be plenty of room. But if they measure 27.5mm or larger...I may be in trouble.