Hi Volks,

I don't recall what the standard speedo error using the 205/70-14 is but the
easiest way to find out the real error is to borrow a GPS and track speed at
30,50,70 mph indicated on the speedo.  The GPS is considerably better than
1% accurate and with several readings you should be able to figure your
speedo error.

I've unabashedly modified a spreadsheet from Tim Smith to do that and other
calculations related to tire size and gear ratio selection.  Pmail for a
copy.  MS Excel.

pensioner