Hello. I just bought some new tires for my F350. They are 235/85/16's. (Same size I took off) BUT the tires I took off were about an inch wider. First time on the highway it felt like my truck was on ice skates. The new ones are very narrow. So I called Walmart and they are going to buy them back, but I have to get some new ones ordered. How wide can I go on the rears? The ones I have read they are 9.5 inches, but they are more like 7.5.