For MFWD tractors I once came across a calculation to check to see if tire sizes were acceptable. I can't remember where I found it, but I saved it to my computer. The calculation is 1-(rear static loaded radius/(front static loaded radius/MFWD ratio)). This calculation checks the overrun on the tires. What I saved says the result of that calculation needs to be within 0.01 and 0.05 to be acceptable.
The MFWD ratio is specific to the tractor, and the download I have lists them all for the Deere compacts. The things I don't know for sure:
1. I only have the published diameter of the tire, not a true static loaded radius that would account for tire squat. I can find that for the larger tires, but not for these small tires.
2. I do not know the true MFWD ratio for the X7 series machines.
3. I don't know if there is any real difference in doing the calculation between a true MFWD system and a hydraulically driven system. I would think not, you've just substituted a hydraulic line for the driveshaft.
But I can make a guess using the published diameters for the tires. For the MFWD ratio I have to assume it's something close to what a 1025r/1023e would be, since they use the same nominal tire dimensions and would want a similar amount of overrun, assuming the hydraulic setup doesn't change anything.
Using the published tire dimensions and the 1025r/1023e MFWD factor I come up with 0.015 for the HDAP tires and 0.034 for the Versa Turfs. So it appears you could swap HDAP's onto the 1025r/1023e machines, which I know people have done. Can you make the swap onto an X7? I'll let you decide. I wish I knew the MFWD ratio and the static loaded radius for sure, it might be in the service manual. I'm expecting delivery of a new X758 in the next week and am trying to make that decision.
The thing to remember is the loaded radius is impacted by a lot of things, like the amount of load on the tractor, and tire pressure. It's not hard to change the static radius of these tires by 0.25 inches by just messing with the tire pressure a little, or putting tiller on the back. So in the end, is the small published difference in tire diameter a big deal in real world conditions?
Would you need to re-level the deck? Yeah probably if you want a really nice cut. But you should do that if you change your tire pressure too.