I've read threads on this topic in the Tires forum and the overwhelming response was don't do it.
I'm not an expert, but it seems like a bad idea because:
- RFT have stiffer sidewalls. That's why they provide great steering response and can support the weight of the car with no air pressure. Having RFT's in front and non-RFT in the rear will cause oversteer.
- There are usually significant differences in the ways different tires respond to various driving conditions, including dry traction, wet traction, turning, braking, etc.
If the front and rear tires respond differently to different conditions, you might not notice much in normal driving, but there might be a huge difference in emergency conditions or when you intentionally push your car. The traction and stability control systems were developed and tested assuming you have the same type of tires on both axles. I've noticed differences when I replaced the rear tires with the exact same type of tires on the front because the new tires have more tread (10/32 instead of 3/32).
But don't take my word for it. This thread will be moved to the Tires forum and you'll hear the same thing from the experts.
The OP states that he wants to put wider tires in the rear than stock. Going wider causes understeer. It's possible that the oversteer caused by the RFT/non-RFT combination will be cancelled out by the understeer of the wider tires, but it's more likely that making these changes will upset the handling balance and who knows what will happen in emergency and edge conditions.