I am running 17.5" rims on the rear and still have the old 17" on the front. I need new tires and took my extra rims to a tire dealer who told me the taper on the inside of the rim might cause the tubeless tire not to seal so well. I have to do some work to clean up the 5 17.5s and am looking at going to 16" rims but need the hubcap clips and I also need the tire to fill up the wheel well - the tire needs to be 30.5" tall.

I don't want to go chrome, black steel will do just fine. This is an old Falstaff beer truck and I want to paint it and fix it up but not hot rod it.
Any experience with rims and tires? 17.5 tires are expensive.