My local, UK, council recyclers will accept 4 tyres only (1 car) at one time but don't expect to see you for a while. This stops the dealers getting free disposal. I was clearing the garage of old wheels with tyres on and dropped my garage man £10 to strip the tyres off 15 wheels. The recyclers were happy to accept all the wheels but invoked the 4 tyre rule on those. Popped in every month or so to get rid of the rest.
In the UK it is standard for the price of a tyre to include fitting, new valve and disposal, often balancing is included too. It's a competitive business. Tyres are more expensive here too although there are some cheap "ditch finders" out there if you look and have no regard to you and your families well being. Some will offer their "special" balance for an extra £5 or so and that will include an enhanced guarantee on the tyre. Not unreasonable but not much help if your alignment is way out and you tyre gets wrecked in 2000 miles!
I have a '92 240 SE with the B200 engine. Came with 14" Scorpio cross spoke wheels and a mixed set of 185/80 tyres. They were changed to a set of 15" Virgos with 195/60 tyres. Perhaps surprisingly these are smaller in diameter than the 185/80/14's. I will buy 195/65/15 when these wear out. I might never get that far but the change will raise the gearing back to normal and the change from 60 to 65 aspect ratio will add a bit of comfort.
Look after your 240 and it will look after you.