Quick Tire Question

dylansword

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Aug 10, 2011
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boise id
Hey guys, Its time for new tires, and ive been doing some research, And i have two questions.

First, why do people run smaller tires on the rear, like 225/45/17 on the front and 255/40/17 on the rear.

And Second, can 265 tires be run on the rear with out any fender rolling? If not, how big can i go?

I plan on lowering 1-2 inches, and i have 17" wheels
Thanks
 

chris_2jz

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Feb 17, 2009
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tampa
I have the mk4 tt's with a 2 inch drop fronts 17X8 225/45/17rears 17X9.5 275/40/17 I didn't have to roll my fenders but it depends on what your rim offset is.

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dylansword

New Member
Aug 10, 2011
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Okay, since you have the smaller tires in the rear, can you tell me why this is so common to run 45 in the front and 40 in the rear?
 

chris_2jz

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Feb 17, 2009
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tampa
Ill be honest the car came that way but to me it seems to level out the car I think using 275/45/17 would "lift" my rear end

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CATarga

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May 22, 2008
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Grass Valley, CA
When looking at metric tires you have to look at all the numbers together to determine the actual size of the tire. There is a metric tire calculator at the end of this page of Drivetrain Calculators, that you might want to look at.

A 225/45/17 tire and a 255/40/17 tire are basically the same size, with the rear actually being a fraction bigger. In inches the fronts would be 24.97x8.85 and the rear would be 25.03x10.039.
 

Jeff Lange

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Mar 29, 2005
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The first number is the width of the tire in mm, the second number is the sidewall aspect ratio (sidewall is a percentage of the width), the third number is the rim diameter.

So a 225/45 tire has a sidewall that is 45% of 225mm (101.25mm), while a 275/40 will have a sidewall that is 40% of 275mm (110mm).

As you can see, the rear tire is actually both wider and taller than the front, even though it is a 40-series tire instead of a 45-series.

Jeff
 

te72

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Mar 26, 2006
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For what it's worth, stock fenders can be run with 275's all around if you have a good offset. Looks good too, but the link Kenny posted is a really good place to read through, and gain knowledge! :)