I found a guy looking to sell his chrome deep dish rims but he says the offset is 27mm and the american muscle website says that the offset is 28mm. Will that be a noticeable difference or did he make an error or did the website make an error? He said the rims are about 2 years old if that helps. Thanks!!

 

You should be fine. Someone probably made a mistake. That is just a 1 mm difference in wheel position.