I think I gave him the right advice. First, off he was not asking about going to 18"s. He asked about a 235 0n the stock 17" SP rims. Second, I told him it was not a good idea to go larger than a 225. Third, I did not say he would be keeping the same exact OD by going to a 235 40 - only that he would not be raising his final drive gearing or raising his ride height as he would have with the 235-45. I still think it's a better choice to go lower rather than taller if he HAS his mind made up to change them, but IMO he's better off staying with the 225's.