Originally Posted by
Kedosto
If your bike was factory equipped with 35c tires, you'll be just fine running 38's. Closer to 45? I doubt it. They may seem a lot wider, especially if the 35's you were running weren't an actual 35 - some are closer to 32-33. Possibly popping off? Seriously doubt that too (as long as you keep them inflated properly). Any bike will handle "awkward" when the bars are turned sharply. I'm pretty sure you're going to get the hang of it eventually.
-Kedosto
I had GT365 38s on my 18 mm internal rims until recently and I measured them at 41 mm with my caliper. She might be a little high but not off the charts. These do run big.
(As an aside, I prefer this to the substantially-smaller-than-advertised continentals that make one wonder whether they have a ruler at their factory.)