Due to how the Freelander transmission works, wiff the front wheels turning slightly faster than the rears, you need to have the same size tyres all round. If you change any, then they need to be done in axle pairs. New ones to the rear always.
You say you’ve replaced the 2 at the rear. Are they the same size as those at the front? Also different makes can have slightly different diameter (therefore circumference too). The greater the difference, the more stress on your transmission causing the vcu to work harder in effect. This puts more stress on the ird and rear diff.
The test below in my sig will allow you to test your vcu to see what it’s doing.