Marty, can you post the page (page 17) from the 70/100 Operator's Manual, where you saw the tire pressure info. The version that we have on line does not appear to have that info. Also please, if you can, post the document number and revision info as found on the back page. It should look like this (which is the version we have here on the forum):
EDIT: Note that the 6-12 rear tires would have been the stock tires for both the 70 and the 100. The 23 x 8.5-12 would have been optional for both the 70 and the 100.
EDIT: Note that the 6-12 rear tires would have been the stock tires for both the 70 and the 100. The 23 x 8.5-12 would have been optional for both the 70 and the 100.