Originally Posted by PJH
Compare it to a GPS if possible.
I did. I used my Navman in France in the Volvo over that 1,800 miles, and it seemed pretty well spot on. Which presumably means my speedo was over-reading, and the bigger tyres corrected it
I think I'll get some new 60's on the front, and put the 65's on the back. And just hope that I don't get a puncture in one of the 65's...