Different size rear tires on tractor

[sigmrelics]

I have a JD 420 that had two 14.9-26 tires on it. One blew out and I replaced it with a 12-26. Both are recommended for this tractor, however, can having two different size tires on the tractor cause any damage to he tractor's drive train?

 

[Tx Jim]

If tires are different diameters then the spider gears in the differential will be turning all the while the rear tires are turning which could shorten the spider gears & shafts which could cause premature failure of spider gears & shafts.

 

[D7E]

I have a 75hp tractor with a 16.9/26 on one side and a 18.4/26 on the other and been that way for 10 years doing 3-400 hrs a year . Will get around to changing it one day

 

[s219]

If the outer diameter is the same, no problem at all.

 

[jd110]

In addition to extra wear and tear on differential gears, unequal traction from different footprint can cause instability in some circumstances.

 

[Zebrafive]

I could see it wanting to turn in the direction of the side with the smaller diameter tire when the diff lock is used.