Ok, so my story... I have a 2001 T4 and I fancied myself some of the 16" BBS alloy wheels (that were original to the red 'i' TDI engine models as an option). I bought a set of these (second hand) from Germany, they came with tyres size 225/60R16 - which were not compliant at all. Bear in mind the original wheels were 15" steels.
However, I passed through the control technic for 4 years with these 16" wheel/tyre combination and they were either never checked OR they didn't mind, not sure which (and my van had a wonderful episode with the CT here concerning the fitment of a Bearlock - its documented somewhere in the forum here - so they've certainly been thorough with my van over the years!).
Last year I decided to replace the aging tyres and wanted to put the right ones (or at least 'authorised' ones). I thought I'd done my homework. I found this website (which admittedly is for Flanders, but they should have the same rules everywhere in Belgium shouldn't they - i say this tongue in cheek...).
www.gocavlaanderen.be
The site is of course in Dutch, but you can translate if required.
I understood this site to tell me that if I chose tyres that were within tolerance of the original tyres (listed in the Certificate of Conformity), then I'd be ok. You can put the original size and the size you want and it will indicate if they're within tolerance. Incidentally the 225/60R16 that were on the wheels for the previous 4 years, were not within the tolerance according this website.
When i went to the garage for the new tyres they told me I had to fit whatever was listed in the C.o.C. and I shouldn't deviate from that - I even showed them the website above and how the size I chose were within the stated tolerance, but they said that didn't matter.
Long story short, I insisted on the tyres as these were the only wheels I have now, but they noted on the invoice that they'd advised me against them - their ass covered. I've subsequently passed the CT again without issue.
Moral of the story, not sure in all honesty. Maybe you get away with it, maybe you don't.
If you want to be 100% then I suggest you go to the CT station and ask someone to clarify what the rules are.
Other option could be (and the garage did suggest me this), you go to the CT with the original wheels (or your winter set) and once you're home you switch them over until the following year's CT...
About the speedometer, funnily enough, with the old tyres the speedo tallied pretty close with a GPS speed reading, but with the new tyres (which in theory have the same circumference as the C.o.C. stated tyre size, there is a difference. Whether or not the GPS speed reading is correct I don't know either, but I thought it interesting to point out.
As for the lift, I couldn't say, I've no experience of that. But the same website has some info about tuning and lowering:
Basisregels, validatieverslag en montagerapport
www.gocavlaanderen.be
Hope this helps? Good luck!
