One of my 65 starfires has 15 inch rims and a trailer hitch
in the options list I heard this is a really rare option shown here as p28. My question is what hubcaps were on it?

 

It would have been a dogbowl cap and probably with a trim ring, but I'm not sure if it was the same cap as used on the 14" wheel. I keep hearing the 1965 15" wheel option used a snap-in cap similar to how a Chevy Rally cap installs. 67-68 used the Toronado dogbowl cap.

My 1974 parts book does not even address the 1965 car with 15" wheel option. It skips from 1964 to 1966, though the part number is the same for 1956, 62-63-64 and 1966 with 15" wheel- grp.5.858 p/n 9701169.

Then in 5.864 it lists a "clip, hub cap retaining" p/n 564692 clip (snap on type) which fits 1949-58, 62-65 exc F85/J88/reinforced wheel, and 1966 5400, 5600, 5800, 98 15" wheel exc 98 CAC (airconditioning).

wmachines and aliensatemybuick have these cars. I think they will be your best bet for what is correct. If I ever saw one with them, I don't remember it.

 

Well, my thinking is that just because it has 15 inch rims, it doesn't mean it came that way (someone could have added them at some point from any car that takes 5 x 5 bolt pattern (I had a set of Ford (I think) truck rims on a old '65 Starfie convertible I owned).

As for the caps, the standard "cheapie" '65 hubcaps (or any dogdish style cap) would look terrible on your car in my opinion. What I would do if I was you is get some chevy wire wheels and add the '65 style 2 bar Olds flippers to them, as described in this thread (last post):

https://classicoldsmobile.com/forums...-fullsize.html

As for how factory 15" inch wheels might have been "dressed" in 1965, I've attached a pic of a 1966 Starfire with 15" police car hubcaps and trim rimgs (I've never been able to find a better image of that era hubcap).

Check out the video below at time 1:20 or so to see another car with these caps:

http://www.youtube.com/watch?v=vJRfrx2Pa9M

 

Group 5.871-wheel trim ring 1965-66/ All-15 IN - For 15 IN wheels...PN 542926... same ring for '67 & '68...catalogue No. 703 '58-'70...

 

My 1st Olds was a pretty loaded 5457 in the late 60's - towing package with 4:33 rear was the most unique option on it!
Wish I still had it, for it's rarity!
Can't remember wheel size for sure, but I think it was 15" - I'm getting old!