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      04-09-2008, 10:35 PM   #1
sredish
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Slightly taller = quicker accel?

From what I could tell in the test drive, your hitting 60 in second gear... would it be possible with a slightly taller tire to accelerate a tad quicker, possibly hitting 60 in first? Also, with a slightly taller tire, the rpms should be a tad lower at a given cruise speed, possibly helping out with mileage... just a thought and it worked well on my truck.

This is what I was thinking of for tire sizes:

Front: 235/45-18 Rear: 245/45-18

or if that's a tad much, maybe a

Front: 235/40-18 Rear: 255/40-18

more options with the 40 series as well.

Any thoughts on this?
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      04-09-2008, 11:21 PM   #2
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Usually a shorter tire will make 0-60 faster, like a lower rear gear. Say you have a 3.08:1 rear with stock tires, if you get shorter tires it like lowering you gear to say 3.23:1. But the top end will suffer. But with the bi-turbo, I don't really know???
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      04-10-2008, 08:57 AM   #3
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A taller tire raises the effective gear ratio, which lowers acceleration. You'll be able to hit higher speeds in each gear, but you'll get there slower.

On top of that you're going to screw up your speedometer.
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      04-10-2008, 10:05 AM   #4
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Quote:
Originally Posted by Jeff1962 View Post
Usually a shorter tire will make 0-60 faster, like a lower rear gear. Say you have a 3.08:1 rear with stock tires, if you get shorter tires it like lowering you gear to say 3.23:1. But the top end will suffer. But with the bi-turbo, I don't really know???
This has been my experiance. Get the aprox same height. A 1/4" taller or shorter isn't a big deal. But get close to stock, which I think is about 25".
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      04-10-2008, 10:09 AM   #5
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Quote:
Originally Posted by sredish View Post
From what I could tell in the test drive, your hitting 60 in second gear... would it be possible with a slightly taller tire to accelerate a tad quicker, possibly hitting 60 in first? Also, with a slightly taller tire, the rpms should be a tad lower at a given cruise speed, possibly helping out with mileage... just a thought and it worked well on my truck.

This is what I was thinking of for tire sizes:

Front: 235/45-18 Rear: 245/45-18

or if that's a tad much, maybe a

Front: 235/40-18 Rear: 255/40-18

more options with the 40 series as well.

Any thoughts on this?

I wouldn't get these sizes. I suggest 225/40/18" front and 255/35/18" rear. This IMHO would be BEST. A little wider, but not too much. Taller/wider adds weight and also slows down accelleration.

Plus the sizes you posted are taller and wider which will probably scrape the wheelwells. I have done alot of mods in the past and found most Factory set-up sports cars are done correctly. Always thinking wider etc is better is wrong in many cases. You might spend ALOT OF $$$ thinking things will be better, then being very unhappy with the results.
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      04-10-2008, 12:14 PM   #6
sredish
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well thanks guys. i'm totally familiar with gearing as I build off road trucks... and regularly work with gearing and tire sizes and so on...

my thinking was if I could gear it up just a tad more to pull more mph in 1st gear, it could help, but my problem is I'm not familiar enough with it at this point to know if the taller gearing will hurt or help... and maybe the deeper gears will be more beneficial for this high revving motor....

from the research I've done, these sizes won't scrape... 265/45/18 rear is where it starts to scrape and the 235/45/18 fits fine on the front and fills the well pretty good.

anyways, points taken.
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      04-10-2008, 12:26 PM   #7
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smaller wheels = faster, down to about 16". who cares about 0-60?
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      04-10-2008, 12:36 PM   #8
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let me just add, i'm not a track star... i'm a daily driver who likes to screw around some... not act like an idiot by no means, but still... i get your point. maybe i'll just drop it an inch or so and go a tad wider to fill the wells.
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      04-10-2008, 12:55 PM   #9
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Be very careful with taller front tires. The aluminum steering arm is sculpted for clearance around the OE setup. If you get too far away from those specs you may have interference with the arm. Check it at full lock and you will see what I mean. A little rubbing is OK for the track, but I doubt you want that in a street car.
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