What size tires did the car come with. The 66 parts book shows following options for RW cars. 14x 5.0, 5.5 and 15 x 5.5 With part numbers.

So if tire was an 8 series it would be the 14 x 5.5 2298523.
There was a deep dish 14x5.5 listed for charger, P, D and under the RW column. 2534702