I'm not sure where you live, but if people were doing this in any state in the US, the thing to do would be to call the EPA and/or DEP (Environmental Protections Agency and the Department of Environmental Protection) and tell them that they are burning the tires specifically, which is very illegal here unless they are burned in an area zoned for tire burning...Burning plastic would be the same thing, along with the furniture if it had varnish/paint/stains etc. The EPA here takes this kind of thing very seriously and usually here it results in very harsh fines and court-costs to discourage them from doing it again. I don't know what contacting local law-enforcement agencies or local county or state governmental officials and agencies would do over here, it would probably vary between the states and local municipalities as to if they would even care let alone do anything about it, however the EPA and DEP over here mean business...Anytime they find out about people and/or businesses who are doing illegal burning, dumping, ground-water contamination, etc. they are right on it...I know, my step-father has been one of the heads of Health and Safety for Penn State University for the last 25+ years, and since Centre County, Pennsylvania and other surrounding counties such as Clearfield and Lycoming Counties have no Hazmat Departments of their own, they all use the Penn State Hazmat team. So any time there is a truck carrying anything toxic that is in an accident on I-80 or I-99, or there is any fire/burning of anything toxic found, or any dumping of chemicals somewhere, or a house/building being torn-down that contains Abestos or lead-pipes, etc., the Penn State Hazmat Team has to be there, including my Step-Father, 24 hours a day...And he is the one who contacts EPA, DEP, etc., whomever the proper government agency is for each specific situation, whenever something like what you're describing is reported. He has to go and get warrants with the Penn State Police and/or one of the local Police Departments to search private properties, privately-owned vehicles, etc. that are anonomously turned-in by someone. Happens all the time...
Usually he gets anonymous calls about someone or a business burning things they shouldn't (lots of burning tires calls), dumping chemicals or used motor-oil into the ground or right into a local stream/lake/pond, and a ton of calls about people who remove the emissions parts from their cars, like the Catalytic Converters, Mufflers, EGR Valves, O2 Sensors, etc. Lots of car dealerships and repair shops dumping used oil, brake fluid, transmission fluids, etc. and burning tires (central PA is in the mountains and is all forest and countryside, so a lot of shops are in the middle of nowhere, or own property in the middle of nowhere)...Anyway, in these situations someone either anonymously calls the local police, the local State Police, or they call the EPA or DEP hotlines. Then they contact the PSU Health and Safety Department, who usually does the testing and removes the evidence, takes photos, etc. So my step-father will get a call from the police or from EPA/DEP, and he'll go to the person or the business along with a Police officer and they'll first ask the person or business owner about the claim and ask to see the area/building, vehicle, etc. If they refuse to let them see it, then they have to apply for a warrant in Bellefonte, PA at the Courthouse. The nice thing is that it's pretty difficult to hide dumping into the ground for a long period of time or burning tire piles that never stop burning, lol...So then if they find that the claim was true, they will either fine the people plus they have to pay for the complete clean-up by the EPA (which can be hundreds of thousands of dollars or more), or they are also arrested depending on what they were doing.
So it's going to just depend where you live and what local and more-so federal environmental laws and agencies your country has...In the US, the EPA and the DEP are federal agencies, but they also have agencies in every US State as well that handle things like you are describing that are on a smaller-scale.
Do you know what your local and/or federal laws are about burning tires? That's going to probably be the only thing they are doing that would be illegal and that could be willingly handled by a local or federal environmental agency...It's going to be very difficult to prove they are burning plastic and furniture because they can clean that evidence up pretty quickly and there aren't going to be remnants of that laying around, and it may not even be illegal where you live...However, burning tires is typically against local and federal laws, especially in an area zoned for private residences....Where is it that they are burning this stuff, inside of their house in a stove/out the chimney, or are they doing it outside in their yard, out in the open? I can't imagine they can burn tires inside of a stove or fireplace in their house, so they have to be doing that outside somewhere, so it's something that local law enforcement and environmental agencies could see, possibly from your property and without having to enter their property....Can you take photos of their burning tire piles? If so, I'd be snapping as many photos as you can, both during and after they burn tires. That's how you're going to get them...
Of course walking next door and talking to them about it would be the first thing you need to do, if only for the sake of formality, so you can tell local law enforcement and environmetal agencies that you have spoken to them about it and they have refused to stop doing it. Have you talked to any of your other neighbors that live near them about what they've been doing? Would any of your neighbors that are also bothered by their burning be willing to accompany you over to their house to speak to them together about their burning? Having multiple neighbors approach them in a nice, polite yet concerned tone about their burning, voicing all of your concerns together at the same time might have multiple results; #1 they might take it more seriously than they would if it was only one neighbor, #2 it might put a little more pressure on them or make them take it more seriously if it's multiple neighbors that are bothered by what they've been doing, for fear that if it's multiple neighbors that have a problem with it that local law-enforcement will take it more seriously too, and #3 it would also probably take a lot of the heat off of you and they would not be only focusing on you or targeting you if it's you along with multiple other neighbors that approach them about the burning....So if you know any of your neighbors well or are friendly with any of them, or at least you know them well enough to know that they'll have your back or that they are probably also bothered by the burning, then I'd start talking to as many of them as you can and see if you can present a united-front....
least then they can breathe fresh air still can't have them in natural sunlight or air for now but one step at a time.
