I am riding a 1990 R80GS with the standard 24l tank. This will allow me a safe 250km radius and up to 350km if fuel consumption is not too high.
Travelling through south america showed me, that this is sufficient. I do not expect any problems in central and north america either neither in Europe.
I heard from other travellers, that in Asia, India and the far east that should be sufficient as well. I also plan to go to central africa - would it be advisable to go for a Acerbis 45l tank or should be the purchase of jerry cans for specific areas be sufficient. I want to travel light and small.

Cheers Jurgen