It depends -

You would not be able to claim a direct expense write-off of your business trailer under the Safe Harbor Election. However, you will be able to claim it was a business asset and take deprecation on your business trailer (and could possibly be eligible for an IRC Section 179 deduction).

Just enter the trailer as an asset under you business summary page.

Please refer to this IRS link for more information about Business Expenses

To enter Business income and expense information in TurboTax, log into your tax return (for TurboTax Online sign-in, click Here and click on "Take me to my return") type "Schedule c" in the search bar then select "jump to Schedule c". TurboTax will guide you in entering this information.