Almost touching is way too close. I was misled by Shimano instructions of having it very close for years. I've found that 5mm between the largest cog's and pulley's teeth is great. Yields plenty of chain wrap on big cog and quieter drivetrain. Per the attached video, also check the b-tension with the chain in big ring and highest cog so there's no belly in the chain (provided chain is proper length). Kyle is does a great job of explaining what b-tension actually does and how to adjust it! FYI, he's a mtb guy but info applies to road bikes too. EDIT: additional thought--if this is a mtb with an after-market extra big gear, you might need a longer (like 25mm) b-tension screw that the RD originally came with.