Your 16" rim size is fine.
Your Car type rally rims with the Truck 5 on 5 bolt pattern will be perfectly fine!
Use them!
It can be stock 16" GM Steel Rims, Ford Rims, Mopar.
They could even be aluminum aftermarket.
The size is 16".
You're good on that part.
What you need to be aware of is is that when someone else creates, manufactures, and offers up for sale as an aftermarket rim for you to buy, ie: your 16" car rally rims with a truck 5 on 5 bolt centers pattern, you are not there, nor is the manufacturer of your rim there at your truck to measure out exactly the maximum back spacing for the rim you have.
We shall offer CAUTION here, as to take the time to measure what you have before you commit to using those rims.
The Aftermarket companies are just making rims available.
They also are of their mindset to expect that you the consumer, will be either wise enough to measure them, or take them to a professional and do all of the neccesary checking.
Make sense?