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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?
 

· 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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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%
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.
 

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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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