I'm on a square setup with 17 x 7.5 inch wheels at 42mm offset

I've got a good bit more room in the back for bigger tires, but with 205/40R17 front and 215/40R17 rear it handles extremely well and I get even tire wear all the way around. I'm changing tires twice as often in the rear. I have a bit of a heavy foot through corners and braking is something I only do at stoplights.

Those are facts, now here are my opinions.

1. I like the wheels you already have better than the ones you're looking at.
2. You need to lower your car.

 

1. You need to lower your car.

Toyota knew a bit or two when only minimally lowering with both Sportivo and Race springs.
Download a suspension geometry program and you´l see that lowering has definite downsides for the McStrut geometry.
This has nothing to do with rim/tye sizes though and has seperate threads.

I think we need to be aware that mods can have different goals. Cornering anything near quick is véry easily compromised because the OEM set up is impressively well sorted. Toyota came out with a réally good optimum for spirited road use.
There are NO easy wins here and just about any improvement in one aspect will cost you more somewhere else.
Improving the looks without a cost in roadholding is quite difficult and improving bóth.... euhmmmm... more challenging still.

 

The original wheel sizes should be fine. It is a very common configuration. We have been running 16x7 +45 front with 195/45-16 tires with no issues. But clearance to the strut is not much, and a +50 will move the wheel almost 1/4" closer to the strut. Depending on tire dimensions, that might get very close We run the same wheel in the rear with a 215 tire and there is plenty of clearance. We are considering going to 17x7 +45 in the rear just for more tire selection options

When people refer to stagger, they are referring to tire width, not wheel width or track width. The stock front track width is wider than the rear. You current wheels don't really change that. The idea of "square" is to run the same tire and wheel combination front and rear. There are pluses, and there are minuses. It has been discussed many times on the forum

My personal opinion is to stick with what you have.

 

Let me know if you are thinking of selling your old wheels...

 

A few things.

One is that larger diameter rims are heavier.
Lower section tyres have stiffer sidewalls and less air volume = more directional stability but less conformation.
The wheel well shape front and rear are not the same an same size rims may make the rear appear smaller.

Here is a handy calculator to see how diffrent sizes of rims/tyres affect the fit

Will they fit? - Wheel and Tyre Calculator | Carnoisseur

A free calculator to compare and check the fit of wheels and tyres - from Carnoisseur

www.carnoisseur.com

One last thing to note is that larger diameter and for the tyre size wider rims are curb magnets.

 

Some thoughts, as I'm on the same quest: as long as the car still runs the 1zz, i'd rather go on a 15x7 F with ET32-36 and 16x8 R with ET28-32

Goal is to maximize grip, while maintaing the driving characteristics and the staggered setup, as OEM as possible. Too much grip will expose the underpowered engine, while it'll make the car a lot more dangerous on the limit

Curious to see what other suggest though!

 

Not even the PFL with 185 front and 205 rear needs wider rubber as the grip is already excellent. Fit grippy summer rubber and the limits are not at thát end.
A set of OEM/KYB shocks in as new condition with ditto springs and the car can easily outhandle the engine.
Please keep in mind that most cars now have rather tired shocks/springs which are not a reference. Thus fitting new would be serious ´upgrade´.

Bottom line is that with fresh shocks/springs and grippy summer rubber the limits of grip are beyond most drivers.

 

So, what size did you get OP? I'm currently checking the wheels on 4wheelonline, and I'm still undecided whether to go for a staggered or square setup.

 

My current wheels are Enkei PF01. 16x7 +43 with 195/45/r16 front, and 17x7 +45 with 215/40/r17 rear.