So a week and 650 miles later (from London to Whitby, around a bit
and back again) I've got good news and bad news.
The good bit is that all four valves took a slight turn with the valve spanner, and since then the tyres have lost maybe up to 1psi over a week. That I can live with.
The bad bit is the tyre fitters, again.
I set off on my road-trip on saturday lunch-time up the M1, and it was the first time I'd been faster than inner-London speeds in the new tyres.
At around 70mph, there were nasty vibrations coming thru the steering wheel, which only got worse if you went faster: that said to me unbalanced wheels!
I thought hard about what to do: turn back to North London and b*ll*ck the garage (on my time), continue on and keep it under 70 (yeah, right), or call Black Circles to see if they would reimburse me for another garage to balance the wheels.
I pulled over in Northampton services and called BC. They immediately understood my problem.
I got put thru to the duty manager, who found me a network-member garage only 10 minutes away (on a saturday afternon!), and off I went.
I got the wheels balanced for free (and got to watch a bit of Jurassic Park while I waited
Turns out one wheel was well out - certainly there were no more vibrations after that!
So either the tyre fitters didn't balance the wheels properly or (more likely IMO) they messed up the balance when they refitted the tyres.
So my conclusions: Black Circles: 10 out of 10 for customer service that continued after
they'd got my money
But the garage in Iverson Road, North London - never again!
ps- in future I will always take a quick lash up the motorway in new tyres