You should have known better Two Bears I am also unable to offer useful information regarding LPG or Oil fired boilers, sorry. Perhaps PM Neilp although he hasn't been around much lately
If you are sure it's wired in correctly than it sounds like product fault to me.
**Edit** and Google found this:-
http://www.pug306.net/forum/archive/index.php/t-43588.html
Graham, they're Hyperblack finish...
What tyres do you have fitted as the wheels are best suited to 245/35/19 and 275/35/19 as we fitted to Phils above...
Can't remember off the top of my head, I'll look in the morning.