I'm contemplating buying a wheelset that is 700c and a width of 23. I fear this may be a dumb question, but can I still put a 25 tire on that? I would like to run a 23 on the front, and a 25 on the rear, so I am not sure if the wheel width of 23 impacts this.
Thanks!!
Yes, you can. No problems there. The only potential issue is the 25mm rear tire clearing the frame, which can be an issue with some older model bikes that weren't designed with wider tires in mind.
As mentioned above, the frame clearance is usually the limiting factor. You could easily run a 28 mm tire on a 19 mm wide rim. It may not have the most aerodynamic profile as the bulge of the tire would be much wider than the width of the rim, but functionally the tire will stay on the rim just fine.
Bike upgrades to gain speed: better wheelsets, a tri-bike, road bike with aerobars, even getting rid of those love handles before getting that lighter bike.