TOM H - re: re-tapping to use over-size plug in a Kohler Head.... YES, it works fine. BT-DT. Think it was about 1992 I rebuilt the K301 in my 129. In about 1993 I was "tuning it up" for spring. Pulled the plug and it looked O-K but even with anti-sieze on the threads it pulled the threads out of the head.
I didn't really want to pull the head on a fresh engine, so I ordered spark plug taps from McMaster-Carr, stopped @ Farm & Fleet and got a Champion D9 plug, widely available. The H10C is 7/16" reach 14 MM threads. The D9 is 1/2" reach 18 MM threads. I rolled the engine over so the intake valve was closed, but exh valve open, wrapped a rag around a compressed air blow gun, stuck it in the muffler outlet to blow the shavings out of the engine, greased up a tap drill and the 18 MM tap and cut the new threads. I had to rework the D9 plug with a DREMEL to shorten the center electrode and the very bottom of the threads a bit because the exh. valve would hit the center electrode and close the gap. If your head has the plug located away from the exh. valve you may not have to rework the plug.
The engine ran GREAT for the next TWELVE years that way.
MARTY G. - re :Vredestein frt tires, I haven't shopped those tires much but I think MILLER TIRE could get them, they show a 3.00 X 4 Vredestein, and I know they handle the 16-6.50 X 8 & 18.8.50 X 8 V61's but don't show them on their website.
I have the same P-C pancake compressor, also have the next size bigger Contractor's twin-tank compressor, and the full 7-1/2 HP 2-stg 80 gal verticle tank compressor in the shop rated 25-26 CFM @ 165 PSI. The big one is what I run air tools & spray paint with. My FIRST compressor was maybe ONE CFM @ 80-90 PSI.... on an 8-10 gal. tank and I painted the 129 with that compressor and a syphon spray gun.
I really don't like the oil-less compressors that well, but it's really great being able to carry the compressor around, plug into a houshold outlet and run nail guns, etc. I used to work for the company that owned P-C before it was sold off to Black&Decker and we used to get some CRAZY deals on reconditioned, old slow moving inventory a couple times a year. P-C & Delta tools are REALLY good stuff. P-C has made contractor grade stuff since elec. power service was common, then was sold to ROCKWELL, had a few of those tools too, and really had to try to wear out even the consumer grade stuff, and bought lots of P-C & Delta for several years, lot of cheap air tools that are handy, but I couldn't justify buying a C-P or I-R.