What are the pros and cons of changing from 17 to 16" rims on 09 jku rubi with TF 2.5 coil lift.
Thanks for your help.

 

what tire size are you planning to run? if you're sticking with your stock tires, there really are no cons to going with a 16" wheel other than the fact there aren't as many tires to choose from compared to a 15" or 17". i personally have not seen anyone have issues with brakes or ball joint clearance with a 16", just a 15". on pavement, a 17" will have less sidewall flex and it will make your jeep feel like it handles better especially if you choose to run a larger tire. and, on off camber situations, this will also help you to feel more stable. i personally would recommend you stick with 17's

 

Planning on 35's when my stock tires wear out.

 

I am shopping for wheels and 35" tires too. Very few choices for 16" wheels and tires. 17" tires run about $100/tire more than 15" tires. I haven't found any claims that 17" wheels/tires are inferior to 15" or 16" wheels/tires. There are plenty of posts by people that prefer the 17's and there are plenty that are happy with their 15's. There are also many that have had both and advise against the 15's or 16's, citing performance issues and clearance issues (ball joints, brakes, drag link flip, etc.). 17" wheels and tires appear to be the best bet for performance, fit and happiness, although at a higher initial cost.