I need some help with understanding tire sized, my rims are stock 17'' and the current tire size I have is 275 40 17, my question is can 235 45 17 fit? and will this size tire stick out?

235 45 17 is less wide tad taller

so what does the 45 mean? i understand 235 is not wide.

235 (mm) is the width of the tire
45 is the sidewall measurement. But this number represents a percentage of the width number (first number). So, it's 45% of 235 mm which is almost 106 mm.
17 (inch) is the diameter of opening in the tire, hence this tire will fit 17 inch rims.

So you have tire that's 235 mm wide with 106 mm sidewall for a 17 inch rim.

FYI, 1 inch = 25.4MM

Matt nailed it on the head. For an easy database, look up 235/45/17s in brand sites like www.nittotire.com, and it will tell you the overall height, and width of the tire, and the recommended wheel size as well.

If you are talking about a first generation camaro, a 17x8 on the front, with a 4.75"-5.0" backsapce with a 235/45/17 is recommended for the front. Rears are usually a 9.5" wide wheel, with a 5.5" backspace, and a 275/40/17.

Hope that helps!

How about for a staggered 17" front and 18" rear set up?

What is the width of the wheel? 235's may not look right on a 9.5" wide wheel.