Max tire that can fit 17" setup

[Tahero]

Hey, so I have the highline veloster that comes with the 18", but the ride is extremely rough, especially because the roads where I live are ******, So I've been thinking to downgrade to a 17" setup and get the highest tire profile I can get to have a smoother ride without messing with the limits, So basically my question is, what is the biggest/highest in terms of tire profile that I can fit on 17" rims without having problems? and is it even going to be worth it, in terms of making the ride smoother?
My English sucks I know sorry!

[Curmudgeon]

You might (?) want to consider 215/55/17 tires...that tire will provide a +1.27" higher sidewall, but the additional 1.54" diameter (larger than the OEM 215/40/18) might cramp the wheelwell.

In that case, the 215/45/17 or 225/45/17 might be a better fit with 0.42" or 0.60" higher sidewalls respectively.

[jkt1954]

Hey, so I have the highline veloster that comes with the 18", but the ride is extremely rough, especially because the roads where I live are ******, So I've been thinking to downgrade to a 17" setup and get the highest tire profile I can get to have a smoother ride without messing with the limits, So basically my question is, what is the biggest/highest in terms of tire profile that I can fit on 17" rims without having problems? and is it even going to be worth it, in terms of making the ride smoother?
My English sucks I know sorry!

Your English writing is excellent -- have you read some of the posts on here? I'm interested in changing from the 18's to 17's when I have to get new tires and will consider this at that time. The roads where I live are pretty good overall and it's not really a rough ride but the 17's would smooth the ride somewhat AND help slightly on fuel costs.

[velogangster]

if you want smooth 16" is the way to go ( 205/55/16)

[Tahero]

I really don't want to go for less than 17" inch rims, A friend of mine did that 16" setup, and yes he claims the ride being a lot smoother, but it makes his V look ridiculous honestly, looks like a 4x4 haha theres alot of space between the rim and the car, I cant really explain what im trying to say here, but anyways, I really need to know whats the maximum side-wall achievable on a 17" rim, whats the tire specs?
Note: Also is there anything else other than increasing the tire's sidewall that would smoothen a car's ride in poor roads? suspension maybe?