Are you having this problem when driving straight or just in turns?
If in turns I would suggest you have the dealer check the front axle steering. The hydraulic section is connected to the steering input and it varies the left and right front wheel speed in turns. When you make a left hard turn this will decrease hydraulic flow to the left front wheel and increase flow to the right wheel. Making a hard right turn the opposite happens. If not balanced out correctly even going in a straight line one front corner could be going faster and the other front corner is turning slower, both causing scuffing.
The other issue is weight, I went from my prior L130 which weighed about 600 lbs. to the x749 about 1300 lbs. and this is very noticeable in damp conditions. While the weight is double on the x749 the tire patch is maybe 40 or 50 % larger. I should add the x749 and x758 use the same size tires. I run the rear tires at 9 psi. and the front tires at 18psi. It is important to keep them even or the mower deck will not cut level.
When you say your lawn is soft is this a new lawn or has it been in place for a year or two?
Just some things to consider before you spend money on new tires as the 26 12 12 hdap tires on your mower have worked out very well for others on the forum. Changing tires may not yield better results and be money lost. I would check for other problems before spending the tire money.
Here is a picture of my lawn mowed with the x749 and no scuffing. You should be able to click the picture and get a closer or expanded view.