I just switched back to my stock wheels this past week for the winter time. I had always suspected that my 17's read a little fast but I was never sure. I now know for sure that they were about as spot-on as they could be. At 60mph with both sets I am at 2100 rpm, and at 70 mph I am at 2500 rpm in both sets. How can the speedo read the same if the 17's are 8/10's of an inch shorter in overall diameter? The only possible explanation I have thought of is that the Kuhmo's have a much stiffer sidewall so maybe they do not flex as much when put under weight as much s the continentals do. That seems a little far-fetched however. Anyone have any thoughts?
235/45/17 Kuhmo 712's = 25.3"
215/60/16 Continentals = 26.1"
235/45/17 Kuhmo 712's = 25.3"
215/60/16 Continentals = 26.1"