16" rims with a 5 bolt pattern

[Zappafan]

Hello to all. I've been reading posts for a while now and have gotten a lot of excellent advice and ideas. I recently switched from a little Euro trash BMW to a 71 C10 (ex costruction truck). It's nice have a vehicle that I can work on myself and not have a mechanic tell me I need a new $1000 brain that may or may not fix the idling problem. The truck is pretty sad to look at right now but I hope to bring it back to it's former glory. I was getting a better door for it a while ago and the fellow who was selling the parts commented on the rims that are on it. He said that he hadn't seen 16" rims with a 5 bolt pattern on a 71 before. Are these rims unusual? I was going to put some truck rallies on it but wondered if I should save the current rims. I'm sure I'll have lots more questions over the next while and will be doing lots of searching on this site.