withdrawing funds from our retirement to purchase vehicles or rv

We are both retired, and are able to live off our ss benefits, totaling $65,000/yr.  Are we able to withdraw funds from our retirement up to a certain amount that would not hurt us on our taxes?  We would be needing to purchase a vehicle and maybe upgrade our RV, but don't want to have it affect our income so much that we end getting put in a tax bracket that would hurt us. 

What would be the most we would be able to withdraw without putting us in the next tax bracket?

Thank you!

Steve and Debbie McGee