Hey everyone, hope you'all are good and staying healthy.

We ran a local season on square 285/30/18 RE71Rs, it took some work but they fit without modifications to the rear fender profile. Enkie RPF1 - 18x10 +38 w/ 5mm~ spacers = +33 iirc <- to clear the rear trailing arms (barely).
The shorter 285/30/18 (24.8") was/is significantly better on spool-up than the taller 265/35/18 (25.3")

oh, and fyi, 30 series tires are a real pain in the ***, we bent two wheels and cracked one :-0

...and about staggered wheel\tire combos. We ran different offsets way back in the day and while yeah, it sucks that you can't rotate the tires, we actually didn't have to buy tires anymore or less than normal, iirc the rears lasted the whole season without issue. That said, heat-cycling and number-of-runs wasn't as much of a thing back then either...

 

If the RE71R is discontinued without replacement, the 200TW 285/30R18 tire selection is sparse.

Given the trend toward wider tires, I'd expect new 285/30R18 tires to be wider than the 285 RE71Rs.

According to TireRack's measurements, the tread width of a 285 RE71R on 10.0" wheel is only 10mm wider than a 265 A052 on a 9.5" wheel. Gearing advantage aside, I wouldn't be surprised if 265 A052s outgripped 285 RE71Rs.

 

I do agree with you, 285's square should be do-able on a 10" width wheel. Granted, you're probably going to have to be at a high ride height out back. But again, there MIGHT not be any 285/30/18 competitive options available shortly.