I'd also like to know why almost round (305 or 190).
I had a look at
http://en.wikipedia.org/wiki/List_of_Fo ... _by_season and the distance became a standard in 1989. Anybody knows why?
Here the actual race distances in 1988 and 1989 (Km rounded):
Race 1988 1989
BRA 301 307
SMA 302 292 (2 hour limit)
MON 260 256
MEX 296 305
CAN 303 303 (2 hour limit)
USA 253 285 (2 hour limit)
FRA 305 305
GBR 310 305
GER 299 305
HUN 305 305
BEL 298 305
ITA 295 307
POR 304 309
SPA 298 311
AUS 310 264 (2 hour limit)
In most cases, the majority is below the average.