I leave a couple of feet between the front of my Miata or Wrangler and the next car ahead. I've been driving since the late 70s and this is the first I've heard of the "botton of the tires" rule of thumb. It wasn't taught back in the day (is it, widely, now?) and it doesn't make much sense to me since it's a function of the size and the shape and height of one's vehicle, which can vary greatly, whereas I know where my front bumper is and I can (usually) clearly see where the rear of the car in front of me is, and hence create the appropriate gap. Sure, I might leave more space if I'm on a steep hill and think the person in front might have a manual (another Miata for example) but that's rare.

Up until very recently people seemed to always keep just a couple of feet between cars at stops like I did. This business of "a car length or two" seems like a very new thing - the past 5 years mostly - and that led me to think it's some kind of stupid new internet cancer. Probably some "influencer" telling his/her audience that you should put your dominance on display at stoplights by pissing people off and preventing them from getting through intersections. Or putting your dominance and alpha-hood on display by blocking them from getting into the turn lane at all. Anything to get attention, anything to show that you're not (truly) a nobody, even when you are, because you have power!

I've only been rear-ended once in 45 years of driving. Being a d*ck on the road in order to (allegedly) absolutely f-ing MAXIMIZE your own self-perceived "safety" (from highly unlikely events) at the expense of everyone else is a totally modern-American sort of thing to do I guess. But I'm not doing it.

Tyres and tarmac!

I got the advice once to make sure you can see the bottom of the tires in front of you. As a general rule, your turning radius tends to align with that. This falls apart with big trailers and snub nose trucks, but it's a good start.

You should just be able to see the ground under the back tires of the car in front of you. That’s the appropriate distance.

Usually this is the result of distracted driving. At a stop light? Perfect time to check your phone! Once the light turns green I give a solid three count then I honk. I'll probably end up shot dead sooner than later but fuck it and fuck those assholes on their phones.

I don't leave any space

I just ram them

...i try to leave enough space not to touch bumpers when the front car's suspension rocks back under acceleration...

I was taught this in driving school. If you’re the last car slowing down, leave a gap of a few car lengths so if a car behind you is going to hit you, it gives you some room to escape either to move up, or enough room to turn out of the lane.

That sounds like some kind of superhero fantasy to me. In what scenario am I about to be rear ended and have enough time to move my car safely?

I usually leave enough space that I could turn into another lane without having to reverse, so if the car in front of me stalls I can go around without too much fuss. That’s like half a car length at best.

On the other hand I had a guy get out of his Jaguar the other day and yell at me a while because I stopped too close to his bumper.

Are 'road sensors that trigger a light change' a real thing? I thought lights are on a timed cycle.