For those that don't know metric 8.8 = about Grade 3 under US standards. Not even grade 5 which most consider the minimum for suspension components.
Actually Grade 5 bolts are pretty much equal to 8.8 metric in terms of tensile strength
8.8 = 85,000 PSI proof load
10.9 = 120,000 PSI proof load
12.9 = 140,000 PSI proof load
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Grade 5 (1/4" - 1") = 85,000 PSI proof load
(1" - 1-1/2") = 74,000 PSI proof load
(1-1/2" - 3") = 55,000 PSI proof load
Grade 8 (All sizes) = 120,000 PSI proof load
There are many others over and under these grades but you get the idea. Most small vehicals I've seen have grade 8.8 bolts as suspension fasteners, untill you get into the larger trucks etc. Anyways, it doesn't hurt to go for the higher grade fasteners. Further info here :
http://www.rigging.net/Bolts.html