Determining minimum dimensions for circular driveway
Architects and traffic engineers have used “Architectural Graphic Standards” by Ramsey and Sleeper since 1932. It’s been updated every 4-5 years by The American Institute of Architects and John Wiley &amp; Sons, Inc.  

They recommend a minimum INSIDE radius of 12’ for sports car, 15’ for sedan, 19’ for SUV’s and Cadillacs and 22’ for pickup trucks with small boat trailers (boat=16’ or less). 

They recommend a minimum OUTSIDE radius of 22’ for sedans, 29’ for SUVs and Cadillacs and 41’ for pickup trucks with small boat trailers. 

We do not provide a curb between the driveway and walkway on the outside radius for “extra” cushion.