Depends on what you want to tow. My 8.5' wide enclosed trailer got into the jacks with a 42" extension so I had to pony back up for the 48" extension. Even with that I need to be careful. For me, the correct answer is to extend the tongue on the trailer and hopefully go back to the 42" extension. Beat to load it up and check with a tape measure. I could easily tow a boat with a 42" extension and have no issues.