Rim Question

[gogo34]

Merry Christmas! I got some "Rover Money" from Santa this morning and it's burning a hole in my wallet. My 1966 IIa currently has tires labeled (sized?) 16 x 7.5 on it. They came with it when I bought it. In addition to the 4 that were mounted on the truck, the PO "threw in" a fifth tire but not the rim. Now, I'd like to know what size rim I need to buy so I can mount the 5th tire. The style of my existing rims appears to be a standard LR rim, solid metal with the small slots around the outside where the hub meets the actual circular rim. Our hosts sell similar looking rims sized 16 x 5.5.

I know there's countless tire/rim choices but, I'm trying to back into my rim size based on an existing tire.

What's my best option?

[antichrist]

There should be part numbers stamped in to yours, if you want to match.