Like the title says, I'm wondering what the biggest /stickiest tires are that will fit on stock 15" aluminum rims. I'm guessing I could get away with 205/60/15, which would be very close for the speedometer. Is it possible to go any bigger than that on stock rims?
The 225/55R15 is larger though difficult to find tires for that size.
Wheel width is your limiting factor. I wouldn't go wider than 205 on the stock 6" wide wheel.