This is a horrible form of protest because it is likely to cause property damage as most people are completely blind and oblivious and will drive on their now deflated tires for a bit before realizing something is wrong.
That will likely ruin the tire and possibly also damage the rim.
Second, you have no idea who you hurt and the repercussions of it.
There’s no immediate “big car = bad person” logic that’s valid.
If you want to protest in a meaningful manner you should support politicians who want to increase taxes for fossil fuels.
There’s a reason the average engine size (and thus vehicle size) is lower in Europe, and it’s not small streets and parking spaces.
Obviously since giant cars never took off here we didn’t scale things to fit, but that’s a chicken and egg thing.