Truck nuts - Stupid? Maybe.
But are they protected free speech? I very much think so, even if I think they're silly. Frankly, I think my country (yes, I'm a yank - I'll get my coat, but not until I'm done,) swings very much in the wrong way on what is or is not protected free speech.
Hatemongers (I won't name any names, but you probably can guess the ones I'm thinking of within three tries,) get a free pass to cause all the emotional mayhem and havoc they want, inciting others to hatred in the process, but moral busybodies see truck nuts and think that those, not hatred spewing from a firehose, is worthy of being suppressed? The priorities on display are skewed.
As for the truck nuts being "offensive," if someone thinks that, then chances are they're the sort of person whose parents refused to allow them to take health classes or sex ed for fear of "sinful thoughts," and who now inflict that woeful ignorance on their own progeny. Crass, yes, rude, yes. Offensive? I don't think so - but even if they are offensive, they're hardly the most offensive thing being slung (literally, in this case) in the name of free speech.
If something being "offensive" is enough to get it banned, then I can name about five groups that need to be disbanded by force of arms - but that won't happen, and it shouldn't. Neither should truck-nadgers be punished by force of law.
Oh, and aside, for those who think that it's "protected free speech" to cut the truck nuts off someone's truck, remember that, "My right to swing my fist ends at another man's nose." That's not free speech, it's *vandalism*, destruction of property, and theft (if you remove said truck-nuts from their rightful place on the trailer hitch of the vehicle in question,) and should be punished appropriately. Same for those who think that someone having a bumper sticker they disagree with or find offensive should be punished with a bucket of paint.
The freedom of speech/expression isn't meant to protect speech or expression that's popular, it's meant to protect that which *isn't.*