I pull a 1952 JD60 in farm stock classes 8500-11000. I have participated in about a dozen pulls now, and while the motor is as I bought it(stock?) except for electronic ignition, I bought some used 15.5 x38 tires from a friend in our club to try and put the power down better. I have always pulled in 1st gear, and was wearing 12.4 tires beforehand. Since the tire change, I am going further, but still always run out of traction before motor. I'm thinking of trading up to 16.9 tires w/23 degree bars, and wondering if I would need to put them on 14" or 16" rims. My current 15.5s are on 12" rims, pulled at 8 to 10 psi, and they're loaded. I don't have very deep pockets, and just want to spend what I have wisely. Thanks for you thoughts in advance.