I went from OEM Dunlops to Metzler 880s (Marathon 150/90 B/15 M/C 80) and noticed that my indicated speed at 5000 rpm went from about 80 to 75 or below. Has anybody noticed a similar change? I haven't checked my speedometer accuracy again. Before, it was pretty close. Should I be running a 160 or 170 size? I do quite a bit of freeway cruising and would like to get that 500-1000 rpm back.