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Discussion Starter · #1 ·
Hey everybody I just have a quick question.... Im planning on buying new rims and I am considering 20s... I just wanna no if i need to re tune my car cause ill be going with a larger rim... I curently have the 19" Brembo wheels.. Will my speedo be affected?
 

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The Blue Dragon
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Depends on the tire size. Changing run diameter will not change speedo, but running a taller or shorter tire will. What size tire do you have now and what size tire do you plan on running? I assume you currently have 255/40r19?
 

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Discussion Starter · #3 ·
Depends on the tire size. Changing run diameter will not change speedo, but running a taller or shorter tire will. What size tire do you have now and what size tire do you plan on running? I assume you currently have 255/40r19?
Yes sir.... I think ill be going 275/35 r20... I really like this set up

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If your running a 255-40-19, any 20 inch tire you choose that is taller will have a very minimal change on your speedo, not enough to worry about imo. 285-30-20 would be the same height I believe, but I would never do a 30 profile unless I had zero wheel gap. 35 profile looks great with 20's.
 

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Discussion Starter · #6 ·
If your running a 255-40-19, any 20 inch tire you choose that is taller will have a very minimal change on your speedo, not enough to worry about imo. 285-30-20 would be the same height I believe, but I would never do a 30 profile unless I had zero wheel gap. 35 profile looks great with 20's.
Thanks for the info... I have eibach prolkits right now so i think the the 20s would fill the wheel wells nicely
 

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Thanks for the info... I have eibach prolkits right now so i think the the 20s would fill the wheel wells nicely
They would, but not with a 285-30-20. I would do a 285-35-20 or a 295-35-20 in the rear. A taller tire will fill more gap. I had 285-30-20's before with a 1.25 inch drop and I hated the wheel gap in the rear.

---------- Post added at 01:06 PM ---------- Previous post was at 01:04 PM ----------

They would, but not with a 285-30-20. I would do a 285-35-20 or a 295-35-20 in the rear. A taller tire will fill more gap. I had 285-30-20's before with a 1.25 inch drop and I hated the wheel gap in the rear.
Oh wait I saw that you said 275-35-20. Your good then.
 

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Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference 255/40-19 4.0in 13.5in 27.0in 84.9in 746 0.0% 275/35-19 3.8in 13.3in 26.6in 83.5in 759 -1.7%
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You want the tire size to match your stock 27" tire as close as possible. And 4/10 of an inch is not close.



You can change the settings in your tuner yourself if you have one providing your tuner left those options open. Not all do.
 

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Tire Size Comparison
Specification Sidewall Radius Diameter Circumference Revs/Mile Difference 255/40-19 4.0in 13.5in 27.0in 84.9in 746 0.0% 275/35-19 3.8in 13.3in 26.6in 83.5in 759 -1.7%
Back to the Calculator

You want the tire size to match your stock 27" tire as close as possible. And 4/10 of an inch is not close.

You can change the settings in your tuner yourself if you have one providing your tuner left those options open. Not all do.
It's actually very close. Depending on the brand of tire, his revolutions will be almost identical. The revolutions are what matter.
 

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My nitto invos are a full inch taller than my stock tires, and the revolution difference was a 746 vs 739. I saw zero difference in my speedo. You can't go by the tire calculators. Certain tires have softer side walls and they flex when driven, which increases the rev per mile.
 

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Discussion Starter · #12 ·
Thank you for your help guys I really apreciate it.... Ive decided to stick with a 19" Vossen cv2 in a matte black....
 
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