Now let me guess, these guys mostly change tyres and exhaust pipes "Kwik" ...ly.
Yes but not the Kwik.. you are thinking off, but a west country Easy...
They fit tires as you say and also do, mechanical work too. They vary from excellent to not so. You would think that fitting tyres would be problem-free for such a place but:
Someone slashed one of the front tires on our car (I think because I parked on a road that they thought was theirs) so after putting the spare on I headed straight to my favorite discount tyre place.
Luckily, they had the right tyre and at a reasonable price- no problems.
The next day I made a 240 mile round trip, and all was well except for front wheel vibration, which went away around 62 MPH. So I drove all the way there and back at 62 MPH.
The next day I was back at Easy... They were most apologetic and immediately re-balanced the wheel- it was slightly out, but not much. I took the car for a spin on the motorway- same vibration, so back to Easy...
To summarize the procedure that followed over the next year:
(1) the tire was changed
(2) the wheel was diagnosed as being bent- the wheel was changed
(3) The suspension was diagnosed as being faulty- the suspension was checked and found to be OK but there was one bush that was suspect
... and so on.
Then, in desperation, I went to another tyre shop. They found that the wheel was out of balance. They balanced it and from then on the car was perfect- no vibrations.
spec