In high heat applications, or in the case of dissimilar metals, dip your fasteners in milk of magnesia. Heat does not adversely affect the residure, and it prevents galvanic corrosion in the threads. The manganese acts as a sacrificial layer, and if either material reacts with it, the oxides formed do not attack the other material. We used Zinc Chromate primer for that in the old days. If you do it that way now, it's Zinc Phosphate (if you can still get THAT where you live) but the old WWII era field answer is milk of magnesia. Still used to this day to install igniters in tens of thousands of Williams-Rolls turbine engines. Great for exhaust bolts.
Also, if you are into shade tree engineering (no skin on the wall here kids!) take the chart in Gary's post. 12 fasteners, 8 MM in diameter and a 5 MM thick disc is 40 square millimeters of bearing area per bolt times 12 bolts is 480 square MM of bearing area, or .744 square inches. Multiply that by the yield strength in the chart and it would take 42,408 Pounds of pressure to yield all 12 bolts. The minimum bearing yield value for a common wheel casting alloy, A356 in the T6 artifically age hardened condition, is 44,000 PSI, so the grade 2 bolt will support more load than the wheel over that area, with an edge marging of 1.5 diameters. Since that's not the case, the bearing yield value of the aluminum is 52000 PSI, which when multiplied by the .744 inches of bearing area, the aluminum stii fails before the grade 2 bolt. Of course that's shit house math, and MANY factors are not taken into account, and that's not how simple it really is, but done correctly, given the shade tree math produces a margin of nearly 20% in favor of the fastener, I'd say even a grade 2 would work just fine in that application. As I said, I'm not an engineer, but I have built and maintained aircraft successfully for over 25 years in spite of them!
PS, a good safety wire job looks trick!