Thanksfor the wakeup HJ. Fearless huh!? That would be nice..... if only it were true..... Anyway, I'm still here, but something came up and my time has been really limited the last few weeks. Another week and I'll be back in shape.
This must be the picture you are thinking of. This was the "super-wide" factory turf tire option on the last of the YM336D. These tires and wheels were a factory option for any of the YM336Ds or JD1050 tractors that used an 8 bolt rear wheel. Not much on the 336 matched the 1050, but the ratios, wheels, and tires were the same. Maybe for the 6 bolt wheels as well, but I've only seen them for the 8 bolt. The only changes required when I changed to these from the Ag setup was to use the corresponding front rims/tires and going to a tapered-head type lug bolt.
Alternately, all of the YM336 tractors could mount a standard turf option that used a skinnier smooth diamond tread balloon tire on the standard Ag rim.
The super wide turfs do make it a lot more stable on slopes, but it does not turn so easily as before. It will plow the ground with the front tires if I try to turn too sharp. It never did that with ags or thinner balloon turfs. To me the tradeoff in stability is worth it. These super wides also lower the tractor a couple of inches.
You are quite correct, any wheel and tire combination can be used as long as the proper front to rear ratio is maintained and the tractor's belly doesn't drag on the ground. The ratio for the late YM336D is 1.694:1. That is the same as saying that 36 turns of the rear axle is exactly equal to 61 turns of the front axle. I measured it. So the trick (for a 336D) is to go to the Firestone and/or Goodyear tire site and select a set of front and rear tires with a rolling circumference ratio that is within 10% of that 1.694:1. Oh, if the tire specification is given as "loaded radius" you multiply by 3.14 to get rolling circumference. DO NOT USE "OVERALL DIAMETER", the real rolling circumference is the only valid number for calculating front to back ratios.
The next step is to buy the recommended rims to fit those tires. The final step is to specify the wheel center has the proper bolt circle (most are standard) and that the centers have sufficient offset so that the tires will clear the tractor as they rotate.
I'll be glad to help on this if I can. Gear boxes and ratios have always held a fascination for me.