Originally Posted by Red Bread
Short answer, replace all four with non-RFT's.
Full answer, It's strongly recommended to not run mixed RFT and non RFT's because the sidewalls are so different that handling can be quite unpleasant. It's also generally cheaper to get all four non-runflats than just replacing the rears with RFT's.
There are all kinds of good non RFT tires out there, but oddly, the one tire I've had that I absolutely hated is the one the OP mentioned, the Toyo T1-R's were downright awful on my M Coupe and I would strongly recommend searching for a different tire.
Thanks for the reply. My front tyres have a good 6-months worth of tread on them so it seems a waste to ditch them and won't be cheap for 4 new corners! Think it may be worth just replacing the rears for RFTS then.. Bridgestone the way to go?