The stock 2011 diesel SR5 rims are 30P 17x7.5 alloy. These rims also fit over the bigger 338mm brakes on the 2008-9 TRD’s so there must be a bit of clearance over the smaller 319mm brakes you have. My guess is steel 16” would go close but you might have clearance issues with alloy 16”.
Don’t go any less offset than 5P as you’ll be illegal and may well run into insurance problems in case of an accident. 5P changes your track by exactly 50mm which in most States is the maximum you can change. Personally I’d stay in the 20-30P range and stay with a tyre the same diameter as your original 265/65/17’s, like a 265/70/16. If you go too much bigger you really should run bigger rotors to overcome the loss in braking from the bigger diameter tyres.