I think a lot of people have broughten up some great points. I think another point to bring up is...well first I would like to ask a question or two. If you buy for example the trailer from your neighbor, are you going to completely drain your savings account? 2. Do you have the room to keep the bigger trailer at your shop or home? Can you keep both trailers on sight? 3. What is realistically the max number of clients you can do with your 5x10? Obviously you want to maximize all profits but buying new equipment is an important thing, doing your homework is the most important part. Your parents may not be fully against you getting the bigger trailer but they want you to do your homework and learn to neogiate. Ex. Are the brakes electric? What is it going to cost to set up the electric brakes set up in your truck? What are the cost of tires and what is the condition of the tires on the used trailer? How are the bearings, and what it would it cost to get them regreased. How much can you do this work or with your folks.? Go to the yards shop around, look around. I know others have said it but I would go to them like I would go to the bank asking for a loan, I know it is your money but go with me. You need a very detailed and well organized plan, print it up put it in a nice three folder with a cover and all. You own this business make it professional. Sit down with them and show them, everything what it will cost to up keep how much you have saved up how much a brand new one is etc. Showing you parents you are this mature, can prove to them you are ready for this new piece of equipment. Its all about research, you need to build a professional built proof argument so when you sit them down they dont have an argument back. One last word of advice, I would pack in as many clients as you can before you buy a trailer. Granted I would have the money ready and a place for that trailer so when you get a new client or two or three you can go get that new trailer and get it working immediatly. The other thing you need to look at it is the yards you work in, will the 16' be too long??? Best of Luck. I hope this helps. If you need any help any where please ask.