I read an article in a car mag about speedo error. Most car makers err on the side of caution, so even the truck will probably be a little off, but much closer than the bike. Try going real fast in front of a school with a speed checker
Also, remember the error is a percentage, so it's like 5mph @ 50, and
10@100 etc. I think the general concencus was somewhere around 8 or 9%, but most people round up I suppose.
