For myself, and most others I would assume, a "normal" speed for traveling over a speed bump would be in the ballpark of 2-8mph for the average parking lot "bump." I would never go over a speed bump at 25mph in anything that I own.

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1985 300D 296,000 miles - Project "Rusty" 1/4 mile in 19.9 sec @ 71mph. It's almost rust free and water proof!

2006 Dodge/Cummins 6-Speed - 670HP 1159ft/lbs