Just purchased a 2020 IS 300 f sport this summer
Looking to buy winter tires for our Canadian climate
Car has 225 40 r 18 on front and 255 35r 18 on rear . Question: Can you mount a standard set of wheels and tires (tires all the same size) so you can rotate them or do you have to maintain the two different size tires for winter?
Dealer wants to stick with the staggered setup (two tire sizes)
Reputable wheel shop has recommended aftermarket rims and 225 40 r18 tires
Any suggestions?

 

I can't answer your question but, regardless of what's possible, it's worth checking with your insurance, and warranty if you have one, if such changes would have any impact.

 

Just go in the middle and run a squared set up closest to the full diameter, if you're too off (forgot the percentage), you will get an error light on the dash in regards to the AWD.
225/40/18 diamter is 25"
255/35/18 diameter = 25"

So you could do 235/35/18 = 24.5" or go the route of doing 225/40/18 all around. Keep in mind, the wheel in the back is half an inch wider than the front, I would probably go with the 235

 

This is what you want and is what I have been using for the last 4 years on my '19 350 AWD F-Sport:

- 17 x 8.0 GTS G505 (or another aftermarket alloy wheel set, preferably one that is hub centric and won't need spacer rings)

- 5 x 114.3mm, 35mm offset

- 225-45-17 Michelin / Bridgestone / General / Yokohama

You can rotate these, and they work exceptionally well for snow. Don't use winter tires on the stock 18" F-Sport wheels.

 

Fellow canadian here! You can definitely use a square setup (all 4 tires same size). But I was told the front caliper is really big on the F-Sport and that not every 17” wheel will fit. Lexus might suggest to stick with the staggered setup so they can sell the tires they have stocked… some other shops might not want to risk interfering with the front caliper and suggest a square 18” setup… but my local Lexus dealership suggested their RWC 17” wheels which will clear the front caliper and 17” winter tires are also a cheaper option!

So I went with Lexus’ recommendation and took their RWC wheels. I bought those on my 2015 IS350 F-Sport and they also fit when I switched to my 2018 IS350 F-Sport. Sadly, they no longer fit on my 2022 IS350 F-Sport (different tire/wheel size, lugnut)… a good reason for me to switch wheels lol

On my ‘15 and ‘18, tire size was 225/45R17 all around for winter setup. Here’s a couple of pic for reference:




* Same wheels/tires different car

 

My 2014 F-Sport AWD has the same staggered tire sizes. I went with a cheap set of 17 X 7 steel wheels wearing 215/50/17 Blizzak WS90 snows. Ugly as sin, but man, do they work good!