21’ Sierra with 4in ready lift, max tire size on stock rims?

[Asmitty]

Before I begin, I’ve seen very contradicting forums stating “yes they will fit” or  “no they won’t”. Currently running 275/60r20 on the stock 20x9 elevation wheels. 4in ready lift sst installed. Currently have about less than half an inch of clearance between my UCA and tire. I’m looking to go 275/65r20. Keeping the same width hopefully should mitigate rubbing, but I’m not sure with an aggressive sidewall etc. picking either nitto ridge graps, Toyo AT3s or possibly BFG. Attached below is photos of the clearance. Was going to consider a 1/4in BORA slip on spacer but would rather stay away from them if I can. Any insight would be great before I drop 2k lol. Thanks.