I had 17" wheels originally and the speedo read over. Now I have 19" wheels with 255 45 19 and it's pretty much spot on.
The speedos can be calibrated using VCDS or similar, so I'd guess that the factory setting could vary depending on what size wheels the van left the factory with. So not all tyre size recommendations will give the same results.
The speedos can be calibrated using VCDS or similar, so I'd guess that the factory setting could vary depending on what size wheels the van left the factory with. So not all tyre size recommendations will give the same results.