....DON'T GO SWIMMING IN THE OCEAN....THE SHARKS WILL EAT YOU!!!!!!!!! ;)
Now you tell me!
I've been diving in/under the shark-infested Pacific Ocean since 1979.
Tell me it's not too late to rectify the error of my ways!
Stock hub bolts are M8x25, head-stamped "7"; 7T corresponds to metric class 8.8 (SAE grade 5), which is categorized as "medium strength". Stronger bolts, metric class 10.9 (SAE grade 8) are readily available at: http://www.nutsandbolts.com/bolts-metric-flange-bolts-jis-c-31_161.html
Even stronger, metric class 12.9 (174Ksi!), socket head bolts are available from McMaster (#95263A633) and they're zinc coated, tumbled not plated, for rust prevention. Some Samurai suppliers have them (class 12.9) too, but not zinc coated.
If you need strength AND bling, ARP sells an exotic high-strength stainless, class 10.9+ (better than US grade 8). Buy 'em at totallystainless.com (#1-2234). They're strong and pretty, but not cheap.
You have choices. No need to tolerate wimpy, rusty hub bolts. I'd try these LONG before drilling and tapping for larger hub bolts. I like the self-centering action of the cone washers and want to keep them.
Torque specs vary widely, depending on the source. One Jeep reference I found and saved, for 8mm, specifies 18 ft-lb for class 8.8, 23 ft-lb for class 10.9 and 27 ft-lb for class 12.9 (all in cast iron; in aluminum it's 22% less). Other references quote cadmium and waxed finishes as several ft-lbs less, and zinc'd surfaces several ft-lbs more. Most fastener torque goes into overcoming friction, which is such a large variable that it's difficult to accurately predict bolt tension, which is what you really want and need. Technique counts for a lot as well. Sliding friction is less than static friction, so make sure the bolt is turning as you reach your chosen torque value, or you'll not hit your target consistently.