I just went to Valleyfair yesterday. I haven't been there in about 7 years and didn't know if I could fit on any rides. Valley fair website made it kind of scary because it says that larger people may not fit on the rides. I am currently 5'2" and 205 and between a 14 and 16 size. Most of my weight is carried in my middle, especially my lower belly. This experience gave me a tremendous amount of anxiety and I was prepared to not go on any rides. My daughter and two nieces were with me and I didn't want to miss out on the fun. Before going, I spent a great deal of time researching whether or not larger people could fit on rides. I found a post from a member here, but it was posted back in the early 2000s. Granted, I didn't go on all of the rides, here is my experience.
The first stop was Steal Venom. I didn't even try this because I had read that it was difficult for larger people. There is a sample seat at the entrance of the ride to try out. Honestly, I was too embarrassed to try it! I started on the Flying Eagles and had no problems. Next ride for me was the Antique cars. Also, no problems here. I went on the Scrambler next. There is a seatbelt restraint as well as a bar across. It was a snug fit, but it worked. The bar was jammed in my belly, but not too uncomfortably.
We ventured onto the Wild Thing after that. I had no problem on this ride either. There is a seatbelt restraint and then each rider has a lap bar that comes down. The bar didn't come down very far for me and it was tight, but it worked. I was able to make it through without being overly uncomfortable. Plus it was a fun ride! The last ride I went on was the Power Tower. I couldn't pull the bar down as far as it needed to go. The girl went through and gave it a good push and it was fine. This was another fun ride.
I know this is not a lot of information, but I hope what's here is worthwhile.