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Discussion Starter #1 (Edited)
just lowered my 15 ats 1 inch in the front and 1.25 in the rear and trying to figure out if a taller tire will fit in the rear. running stock 19 inch wheels. Oem tire size is fronts 225/35r19 rears are 255/30r19. Anyone know why they put a shorter side wall on the rear. I was wanting to go with the same size in the rear as the front . didnt know if there was a reasoning for gm to run a thinner side wall on the rear. also was wondering how wide i can go. just did lowering springs still have the stock shocks.
 

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Discussion Starter #2
well went ahead and did it. they fit just fine just went to a 255/35r19 instead of the 255/30r19. think it looks way better no issue with rubbing.
 

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2013 3.6 RWD Premium - 2006 BMW Z4M
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225/35/19 and 255/30/19 are as close as you can get to the same sidewall height and overall diameter. Theoretically (tires are never perfect) the "35 height" is 35% of the 225mm or 78.75mm and the 255/30/19 the "30" is 30% of the 255 or 76.5 mm. If you went to 255/35/19 you would have 89.25 which is much taller.

Or use an online calculator Tire size calculator

in inches your front sidewall is estimated at 3.1" and the rear is 3", close as you can get to equal.
 

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Discussion Starter #7
thank you!
 

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2018 ATS 2.0T 6 Speed
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I hope you don't have AWD. 1/2" will eat your center diff


As an example of different tire diameters resulting from tires worn to different tread depths, we'll compare two 225/45R17-sized tires, a new tire with its original tread depth of 10/32-inch and a second tire worn to 8/32-inch of remaining tread depth. The new 225/45R17-sized tire has a calculated diameter of 24.97", a circumference of 78.44" and will roll 835 times each mile. The same tire worn to 8/32-inch of remaining tread depth is calculated to be 1/8" shorter with a diameter of 24.84", have a circumference of 78.04" and will roll 839 times per mile. While the difference of 1/8" in overall diameter doesn't seem excessive, the resulting 4 revolutions per mile difference can place a continuous strain on the tires and vehicle's driveline. Obviously, the greater the difference in the tires' circumferences, the greater the resulting strain.
 

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I hope you don't have AWD. 1/2" will eat your center diff


As an example of different tire diameters resulting from tires worn to different tread depths, we'll compare two 225/45R17-sized tires, a new tire with its original tread depth of 10/32-inch and a second tire worn to 8/32-inch of remaining tread depth. The new 225/45R17-sized tire has a calculated diameter of 24.97", a circumference of 78.44" and will roll 835 times each mile. The same tire worn to 8/32-inch of remaining tread depth is calculated to be 1/8" shorter with a diameter of 24.84", have a circumference of 78.04" and will roll 839 times per mile. While the difference of 1/8" in overall diameter doesn't seem excessive, the resulting 4 revolutions per mile difference can place a continuous strain on the tires and vehicle's driveline. Obviously, the greater the difference in the tires' circumferences, the greater the resulting strain.
I really don't think its that serious, been in the business for while. Having a tire that has out of balance issues, uneven wear or a shifted belt is 10x worse than running tires that have different tread depths. He'll be more than fine, and depending on the tires he selects, he could be better off. The run flats had horrible handling and vibration compared to other tires, so he could easily be putting himself ahead.
 

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I really don't think its that serious, been in the business for while. Having a tire that has out of balance issues, uneven wear or a shifted belt is 10x worse than running tires that have different tread depths. He'll be more than fine, and depending on the tires he selects, he could be better off. The run flats had horrible handling and vibration compared to other tires, so he could easily be putting himself ahead.
The problem is not tire tread depth, it is the fact that his tires are two different heights. That will cause binding issues in an AWD car. The new tread on the rear and worn treads on the front will only exacerbate the problem.
 

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Discussion Starter #13
I really don't think its that serious, been in the business for while. Having a tire that has out of balance issues, uneven wear or a shifted belt is 10x worse than running tires that have different tread depths. He'll be more than fine, and depending on the tires he selects, he could be better off. The run flats had horrible handling and vibration compared to other tires, so he could easily be putting himself ahead.
i went with continental extremecontacts 225/35zr19 fronts and 255/35zr19 in the rear
 

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Discussion Starter #17
The fitment looks great, lowered the right amount so you don't curb anything, but also has curb appeal.
thank you! just the start with it. hopefully will have some more stuff done at the end of the year. got to finish my truck project first. then it will be getting some performance upgrades.
 

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