I have 17" x 8.5" wheels and I need new tires. Which of these three tire sizes (255 50 17 or 255 45 17 or 255 40 17) would provide best traction in straight line acceleration and which would be best for hard conrering?

 

they're all very close; not enough difference to make a huge difference. I'd go for the 45 profile because the height is very close to stock.

 

Thanks for the reply. I do want my speedo to be fairly accurate. I put 3.73 gears in it and swapped the speedo gears at the same time. It came out very close to perfect. I suppose I should crunch the numbers and find out which size tire would get me the most speedo accuracy.

Will the 40 series tires provide a wider contact patch?

 

It may. It varies on the brand & model of tyre, believe it or not. Visit the tire mfgr's website and look up the specs for a given size. Might be 0.0", might be 0.1", might be more.

Your tire height information will be there also (so as to make sure your speedo is kosher.)