Re: GT rubber ideas
The Eagle F1s on the front wheels of my GT JTD lasted 20,000 miles util they were at the 1.6mm legal limit. I changed them a fortnight ago for new Eagle F1s and the car feels so much better. As the JTD has the same torque as the V6 it seems reasonable for them to wear the fronts at a similar rate.
If the rears are okay, I'd just put two new ones on the front. If the wear rate is the same as mine, I reckon the rears will just be down to the legal limit when you're new set of fronts need replacing. For the record, at 20,000 miles my fronts were on 1.6mm and rears 6.0mm tread.