I grew up in the NE where Chavs are called Charvas as a couple of people have pointed out.
It wasn't exactly a term used as an 'abuse of the underclass' but a way of describing a certain look and attitude and other characteristics.
Look: (bearing in mind I grew up in 80s/90s)
Men: tracksuits and other sports gear with gold chains, earrings, big trainers, very short hair greased forwards, caps, pitbulls
Women: bad highlights/perms, tatoos, gold, 2-3 rings on every finger, multiple earrings, lots of make up, orange face and everything else white, (pre spray-tan era) pitbulls, inappropriately revealing clothes.
I never saw a Charva in designer gear in the NE.
Attitude: this was quite important: aggressive, often bullies at school, 'cool' to be poor and underachieve at school, hatred of anyone 'rich' 'posh' or a 'swot', hanging around in gangs, fighting, missing school, lots of smoking, sex, alcohol and drugs at a young age.
Characteristics
Very, very broad local accent. Little respect for authority. Tendency towards football hooliganism.
Overwhelmingly they did live on council estate (accused of being a posh fucker otherwise) and were of a lower socio-economic group.
However, the attitude was a huge part. A non-obnoxious, non-aggressive person who looked/dressed like a Charva and had a low income / lived on council estate wasn't automatically one. A Charva wasn't given as a label to just anyone it was quite a specific blend of characteristics.
When I moved to London I noticed the term Chav used far more broadly and to people that wouldn't be considered a Charva. Designer-clad Chavs also common.
I've lived overseas for 8 years and they don't really have chavs here. I am often asked to describe what one is.
They do have different local equivalents though, which I struggle to understand fully. Again, it's a combination of fashion, income, attitude.