Can anybody help me
 

I just recently purchased four Rally caps for my 65 Chevy truck. The advertisement stated that they would fit 6 stud rims. Once I tried them on I very quickly realized that this wasn't true. The diameter for the rally caps is 7inches, while the diameter of the rims is 8 1/2 to 8 3/4 inches.
Has anybody encountered this problem? Has anybody found a solution to the problem? I really like the looks of the rally caps and would like to use them.
If anybody has a solution I would greatly appreciate any help.
I am using the stock rims.

Thanks

Paul S