So I love my Grand Prix GXP all except for the gear ratio suuucckckkksssssss! There is no reason I should be able to run all the way up to 108mph in second gear and I honestly wish the TCM was retuned so I could downshift into first at 45MPH since it runs all the way out to the 50-55ish MPH range anyway.
I know changing gear ratios is the proper way to fix my one and only real complaint about this car, however being that we have transaxles and I do not have the time nor money to invest in doing this I was interested in maybe going about this with a lower profile tire. Its time for me to replace my tires soon and I was interested in moving to a 255/35/18 instead of the stock 255/45/18. It looks like the effective gear ratio would be increased about 0.24 - so it would be like going from 3.29s to 3.53s if I did the math correctly. Is this a kind of change that would provide a somewhat noticeable increase in acceleration? I would also have less sidewall which would mean better cornering correct?
