55 is a civi speed rating, so is 25, and 10 as well. Have you ever exceeded the speed limit? These are set on standards to keep people safe, but without a doubt I bet you have once or twice. Every vehicle made can exceed the posted speed limits on some roads, but we don't limit all the vehicles to the lowest speed limit. So the dangers of having a truck capable of going over 55, (FMTV is rated for 58, some tires limited to speeds of 55) are no more dangerous than your car that can do 90+. The danger comes in when you exceed the limits. I will say again I'm installing high speed gears to lower the rpms at 55, this is to reduce wear, increase MPG, it also brings the transmission ratios in to a speed range where they were designed. I for one would not want to be in the FMTV doing 81, I also don't want to run 2600 rpm at 55.
Anytime you exceed limits you assume assume risk and liability. From speed limits, safe driving distances (tailgaters)tire ratings, corner speeds, and all the rest. I challenge anyone reading this, if they have any trailers to go look up the speed rating on the tires. Many trailers have biased based tires with 55mph speed ratings. I know this after towing boats up and down the west coast as part of my job.
Its not always about going faster.... and in the event of an accident and one was exceeding equipment ratings it provides the law one more reason to hammer you as well as a reason for your insurance company to not cover you.
Back story on tire speed ratings has a lot to do with heat buildup, higher speeds higher heat, heavy loads equal higher heat as well. Heat destroys tires.
