My distrust of part worns is nothing to do with with buying part worn tyres on alloys etc. You get used tyres with used alloys and used cars, and I have no issue with this at all.
It's just buying JUST used tyres seems so... wrong.
Have you ever been to your local part warn tyre centre? It's full of shifty looking cheapskate chavs in rattly old bangers trying desperate to save a tenner on a tyre, and the big thing for me is where exactly do these tyres come from?
We know where tyres on alloys or used cars from from - someone upgrades alloys, or changes cars, the wheels and tyres are spare. Sorted.
But just tyres? Who here will change perfectly good tyres with plenty of tread left on them? Virtually nobody - the only time you'll do it is when you've lost confidence in the tyre - such as with GT3 - and this is a) hardly an everyday thing and b) would you want a used tyre somebody else has no confidence with?
So the next theory about where they come from. Accident writeoffs. Strip the wheels, sell the tyres to the part warn chav-centres. Yes, good idea. Except you've NO idea how the tyre coped in the accident. It could have been a simple bump on an old car, thus no problem. Or it could have been a damn huge smash with the tyres subjected to all sorts of unusual forces. You just don't know. Why risk it?
Last remaining theory, they come from abroad where laws are stricter. I've heard things like 'well they replace tyres sooner in Germany'. They probably do. Why? Well because tyre performance gets worse when the tyre wears - although a tyre with tread depth of 2.5mm is legal here, it isnt going to perform as well as one with 4mm in the wet. So why put other countries cast offs on your car?
You don't save THAT much money but there are so many unanswered questions about them.
Frankly, I don't risk something as important as tyres and I won't gamble tyre quality by buying used tyres to save myself a tenner or so a quarter. If you've got 17" alloys you've probably got a reasonably decent car - ask yourself if you can afford to run it properly if you need to turn to second hand tyres to keep it on the road.
What next? Used air filter anyone? Part warn oil filters? Can I interest anyone in a used clutch?