hello,

i just replaced my wheelset and noticed that the new rim width is bigger than the old one. the old one is 22mm wide and the new one is 25mm wide. i use the same tires 700 x 23. my question is - is what is the effect of these to my ride/efficiency/etc? if any?

It's insignificant. You'll never feel it or see it in your speeds.
As an aside, unless you're a lightweight (140 pounds or under), 23mm tires probably aren't your best choice for all-around riding. You might try a set of 28s or even 32s if they'll fit your bike. The rims will be no problem--I've used tires from 21mm to 41mm on the same 25mm rims with no problems at all.

Velo Dog, can you explain why a 23mm tire isn't a good choice for a lightweight? I'm all of 130 lbs so your advice your be great! I will say that I am fairly new to cycling and that after I put about 800 miles on my current tires descents at high speeds began to feel a bit unstable. Not like I was about to topple over or anything, just a little precarious. I have played around with my tire pressure but I don't really notice a difference. Have 1900 miles on the tires now, and thought maybe it was time to replace them? Or get a different tire altogether?

First of all, rim "width" is different from rim "depth".

Your rims aren't 22 or 25 mm "wide", your tires would fall off. Your rims are 25 mm "deep" (from outside to inside, measured radially).

And no, that 3 mm won't make a difference in the ride. The wheels could ride better/worse, but it won't be because of that small change in rim depth.

Second, 23 mm tires are fine for you. If you were heavier you might try riding 25 for more comfort, but it won't make much difference even at a higher weight.