JD 770 AG to R4 tire conversion

[gregz]

After using the search box I have found most info needed but have a few questions. My 770 has AG tires and I am thinking of converting to R4. My rear tires now are AG 12.4 -16. I can buy a perfect set of Goodyear 12.4-16 R4,cheap.
Is this a direct tire swap.
Next in simple terms what will I need for the front, currently has AG 6.00-12
what front wheel size
What front tire size
Thank in advance
gregz

 

[Villengineer]

The 12.4-16 R4 should mount on your rims, but you will have to get the rolling circumference for those tires and calculate the necessary rolling circumference for the fronts to maintain the correct ratio or you will mess up your drive line. The "factory" R4 sizes are 25-8.5-14 on the front and 19.5-15 on the rear. The John Deere R4 front rim is the same one they used for the R3's (turfs). It may be easier/cheaper to find a used or take-off set from a 790 or 3005.