235 indicates the width of the tire and depending on the height of the sidewall, may allow for more clearance.
235/35r18 is probably your best option to avoid a roll, though it will likely be a smaller rolling diameter so it will alter your speedo accuracy and fuel consumption.
245/35r18 is my tire size so being the same profile, depending on the tire brand, you could theoretically gain 5 mm clearance on both ends.
I also have a wide 245 tire. Toyo proxes t1 sports have a "wide profile" design, so other 245's might have fit without rubbing whereas mine did...simply based on the model tire I purchased.