255/55/18 on my 2006 GT with 18x8.5" rims

MrFast

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I am looking at a bigger tire size for my 2006 GT with the stock 18x8.5" rims. I was thinking of the 255/55 size that measures 29" diameter (stock tire 235/50/18 is 27.3") on the rear to fill up the wheel well with my stock ride height set up. Has anyone done this? I know it seems a bit tall. I might also consider them for the front as well if they fit. My tire of choice:
ContinentalExtremeContact
 

stkjock

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too tall IMHO, a 28" really filled up the well on the rear, take a look at the rears on mine, 255/45 work nicely on these cars on all 4 corners

a 29" with all that sidewall would hurt the handling as well I believe.

DSCN2920.JPG
 

GriffX

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and the effectiveness of the brakes is going down due to the longer lever
 

MrFast

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Thanks for the advice. Looks like 255/45/18 is 27.0", a bit shorter than the factory stock tire 235/50/18 which is 27.3". I was hoping for a taller tire, so maybe 245/55/18 at 28.6 might be good. Still wondering if anyone has tried a taller tire on these stock rims on the rear and how they actually felt. Maybe I am on my own here with most folks lowering their car and getting skinny wide tires. I prefer a "smoother" ride for this car at this time, and not looking for road course performance (I have another car for that reference picture below).
2022 Oct WGI 7.jpg
 

Dino Dino Bambino

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255/45 work nicely on these cars on all 4 corners.
That's what I'm running on my 18" rims. I've also kept the stock height suspension to ensure that I can clear speed bumps without scraping the exhaust (ground clearance at lowest point is 5.2").
 

MrFast

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JC, yes it is. Picture is from Watkins Glen Internation Raceway. SRT6 is not a common visitor at the tracks, so I get asked "what is that?" a lot.

Dino, thanks for the picture as reference! Our cars look good in red!
 

07 Boss

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28.8", basically 29", This was with ProKit springs. Never rubbed and these are on 10" rims. You should have zero issues with the 8.5" wheel and 29" tall tire. It will fill the wheel well nicely. Just remember that it will effect your final drive ratio. I have 4.10 gears and the are effectively like running a 3.83 gear ratio in the rear.

 

zoomerman46

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Running pretty much same configuration as some of you guys.Fronts are 255/45/18 Nitto on 9in rims and rears are 295/45/18 on 10in rims also Nitto. Front suspension stock except for upgraded shocks and GT500 upper mounts. Rears upgraded panhard bar and Rousch rear springs lowered 1 1/2 in. no issues have run this for the last 10 or more years.

DSC_2688-001.JPG
 

MrFast

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20240530_163745.jpg
Just a follow up. I went with 235 55 18 being a 28.2" tall tire. Works for me. Big change from the 245 40 18 tire at 25.7" tall from when I purchased the car last year.
 

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