Draw time radius around lat/long on map

As suggested in the comments, you can sign up to a service like Travel Time Platform (which I'm using in this example) and use their API to get the possible destinations given a starting point.

Then you can plot this on a map using Google Maps (in my googleway package)

appId <- "TravelTime_APP_ID"
apiKey <- "TravelTime_API_KEY"
mapKey <- "GOOGLE_MAPS_API_KEY"

library(httr)
library(googleway)
library(jsonlite)

location <- c(25.9840, -80.2821)
driveTime <- 2 * 60 * 60

## London example
## location <- c(51.507609, -0.128315)

## sign up to http://www.traveltimeplatform.com/ and get an API key
## and use their 'Time Map' API 

url <- "http://api.traveltimeapp.com/v4/time-map"

requestBody <- paste0('{ 
"departure_searches" : [ 
  {"id" : "test", 
  "coords": {"lat":', location[1], ', "lng":', location[2],' }, 
  "transportation" : {"type" : "driving"} ,
  "travel_time" : ', driveTime, ',
  "departure_time" : "2017-05-03T08:00:00z"
  } 
 ] 
}')

res <- httr::POST(url = url,
                     httr::add_headers('Content-Type' = 'application/json'),
                     httr::add_headers('Accept' = 'application/json'),
                     httr::add_headers('X-Application-Id' = appId),
                     httr::add_headers('X-Api-Key' = apiKey),
                     body = requestBody,
                     encode = "json")

res <- jsonlite::fromJSON(as.character(res))

pl <- lapply(res$results$shapes[[1]]$shell, function(x){
    googleway::encode_pl(lat = x[['lat']], lon = x[['lng']])
})

df <- data.frame(polyline = unlist(pl))

df_marker <- data.frame(lat = location[1], lon = location[2])

google_map(key = mapKey) %>%
    add_markers(data = df_marker) %>%
    add_polylines(data = df, polyline = "polyline") 

If you want to render in leaflet and use a free isochrone service, this is a pretty neat option. There is a limit of 2 hours drive away though.

devtools::install_github("tarakc02/rmapzen")
library(rmapzen)
Sys.setenv(MAPZEN_KEY = "") # get for free at https://mapzen.com/

marimar <- mz_geocode("Marimar, FL")
isos <- mz_isochrone(
  marimar,
  costing_model = mz_costing$auto(),
  contours = mz_contours(c(60 * 2))  # 2 hours 
)

library(leaflet)
leaflet(as_sp(isos)) %>%
  addProviderTiles("CartoDB.DarkMatter") %>%
  addPolygons(color = ~paste0("#", color), weight = 1)