I’m planning on getting a set of wheels for winter. I don’t want to deal with the staggered wheels. Can the front wheels with the same offer can be used for the rear as well for a square set up?

 

It's not ideal, but it should work. The difference in offset front to rear is 9mm and the difference in width is an inch (25mm), so you should be OK with front wheels in the back.

 

Thanks!
what is ideal then? I plan on putting snow tires from mid November to early April. That’s quite a bit of run time.

 

Ideal is the same offsets as OEM. That keeps the wheel centerline in the right place to minimize wheel bearing wear and optimize the geometry the factory worked hard to achieve.

 

What tire size for square set up on oem wheels.
255? is that too much of stretch on the rear wheel?

 

255 is not very good on a 9 1/2" wheel (the MkIV Supra came from the factory like that). Far worse on a 10" wheel. 255 works best on 8 1/2" or 9", so if you have 9" wheels (fronts) on all four corners, you could get away with 255's for a square setup.

 

I just bought a set of ‘15 RCF rims so they’re 19x9 in the front and 19x10 in the rear.
If 255 is too stretched for the 10” rear, will 265 on the 9” front be too much?
I have a feeling I will end up doing staggered for winter tires as well just to keep it at factory specs.

 

^^^^First keep in mind that Winter tires are not available in the myriad of sizes available for Summers or All Seasons. The OD (outer diameter) of stock GSF tires are 26" in front and 26.6" in back. To stay close to that a 235/40/19 tire would be an available size in a winter tire, but would not be good for a 10" wheel. 265/40/19 would be larger in diameter but would mount on both wheels. See attached:

 

The GS350 AWD uses the same size wheel all around, so does the Base and Lux model.

 

I was going to do Michelin Alpin 5 which Costco has in stock staggered sizes.