Read up on
this thread.
The theory goes that you want a square contact patch running at the highest PSI your tire will allow. I'd go measure your contact patch of your current tires at max sidewall PSI. If it is undersquare, go skinnier. If it is oversquare, stay put.
Stuff gets complicated with changing contact patch geometry (turns circular at higher PSI) and uneven weight distribution in the car. The ideal situation would probably be running different width tires front and back.
This theory has never been tested, so take it for what it is worth. If you are in the market for new tires, I'd go for LRR models.
- LostCause