The only way you're going to go 65-70 mph with 5klbs and a 2 door runner is to drop them out of a plane so I'm not too concerned about the safety of it. My pretty decent running 22r can't even lug my rig up to 70 without a tailwind 
I dunno My 87 22r P/U with New 30x9.50 TXR's does 70 no prob. Then again going up this one hill on I-90 There always seems to be a head wind and even then i keep a sustained 70mph. However I do not recomend going all "Fast and Furious" with our yotas. At 86mph things are gonna get real crazy. HAHA
