I was going to do this, I had my wheel with me on Big Island, one of the security personnel at the area where you park your car told me the gravel road is off limits to motorized vehicles. I didn't feel like arguing so I went ahead and rented a bike like everyone else. The local that rented me the bike told me I should've just tried it, in hindsight I should have. I'm still 50-50 on whether it would have been possible to go all the way, the last 25% of it gets really sketchy with very lose gravel. It was almost too sketchy even on a bike. You have to read the road and stay on the portion where the gravel has been compacted by the local cars. If you do this, I'd advise on bringing a lock. After the road ends, there is a few hundred yards of walking/jumping over jagged lava rocks. Everyone leave their bikes, I think it would suck having to traverse that area lugging a 40lb wheel.