Toyota HiLux 2002: Which tyres will keep my speedo correct?

I have gone from 14x5.5-inch rims with 195/Rx14 tyres on my 2002 Toyota Hilux Extra cab to 15x7-inch rims and I'd like to know what tyres to fit to keep my speedo correct. Some dealers are saying 60 others 65. My preferred tyre size is a 235 profile, if not then a 215. What can you suggest?