I recently purchased a lexus is200t 2017. I'm looking for suggestions on a winter tire setup. Any suggestions? Is it necessary to go with the staggered setup 225/40R18 (front) and 225/35R18 (rear)?

 

Welcome to the forum!

The IS200t has the same brakes as the IS300 (RWD and AWD) and IS350 (RWD and AWD)...for the purposes of fitting winter wheels.

Check out these threads that discuss this very topic:
https://www.clublexus.com/forums/is-...sport-awd.html
https://www.clublexus.com/forums/is-...ter-setup.html
https://www.clublexus.com/forums/is-...0-f-sport.html
https://www.clublexus.com/forums/is-...good-idea.html
https://www.clublexus.com/forums/is-...is350-awd.html

 

I just run a square 225/40R18 setup all around for winter. Doesn't snow enough in the GTA for me to go through the effort of looking for 17s.

 

Thanks! So running a squared setup is fine for RWD?

 

Most run a square setup for winter...so yes, it's fine even for RWD.

 

Does the rear feel weird during the winter since you downsized from 255?

 

While you wait for m1919 to respond, pretty much anyone with a winter setup show have downsized tires.
The downsizing is really the width of the tire, as the height is the same between 225/40 and 255/35. I run 17's that are 225/45/17...which is also the same height as the aforementioned.
For winter driving it's actually beneficial to have narrower tires when driving through snow. When you drive on dry cold pavement though, it's easier to 'overpower' the rear wheels, as there is less rubber on the road.
However between AWD and all the safety systems onboard, once you have decent tires it's fairly hard to get into the weeds.

 

Bit more oversteer, but not enough to be that noticeable during normal driving.

My winter wheel and tire combo seem to be lighter than stock, so the car during dry weather seems to have a bit more get up and go.