What size tire iron do I need & other questions...

I thought a tire iron was something used to take the tire off the rim. You can go to an auto parts store and ask if you can try one of their lug nut wrenches on your wheel to see which size you need. Even if you have to buy it and take it home, if you just use it to measure and do not booger it up, you can return it. Or just buy one of the four way wrenches that have different sizes on it. Jim