What are the disadvantages of Changing rims on a car?

I want to change my original honda 16" rims but same size 16 " with flat tire.is there any disadvantage? Model: Honda accord and Year:2009, any advice if i change 16'' to 17'' ?

Sure, you can mount 17" tires and rims on your Accord if you wish. As a matter of fact Honda used a 17 inch rim and tire package on the Accord EX-L straight from the factory. So you need to be hunting for 17x7.5 rims with a 5-114 bolt pattern. Top them off with a quality set of 225/50-17 sized tires and you will be good to go.

First, learn proper terminology. The Rim is the outermost part of the wheel, that the tire is mounted on. The rim is then connected to the hub via spokes, the center section. You want wheels, not just rims.

Now, with the grammar lesson out of the way… The answer to your question is… It depends.

If you stick with a 16" wheel, the differences will be negligible. There will be so little difference you won't notice.

If you change the wheel size though, there's a few disadvantages.
Tires for 17" wheels are more expensive than for 16" wheels.
Because the tires have a shorter sidewall the ride will be more harsh.
You will have less choices of normal tires and will end up with more choices of faster wearing performance oriented tires, so you will be replacing more expensive tires, more often.
Metal weighs more than rubber. That's just a fact of life. By increasing wheel diameter, you're increasing the amount of heavier material and reducing the amount of lighter material. This can slow down acceleration (because an increase of rotating mass has a much higher impact on acceleration than the same weight to the car…2lbs from a wheel is like 20lbs from the car) and also decrease fuel economy, even with the tire diameter and width staying the same.

Advantages?
17" wheels (to many people) look better than 16".
The stiffer, shorter sidewall will flex less, so you have better handling.
YOu will have better turn-in response.
Stopping distances will decrease.
All of those effects will be amplified if you use stickier tires than what you currently have.

There's no major disadvantage. Maybe a slight decrease in fuel economy. Nothing major. But changing your rim size will mess up your speedometer so if you change them you will need to get it calibrated.