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Discussion Starter #1
I just bought a 2017 R/T with:
- Super Track Pack
- WRT black wheels 9"

The car came with the 245 tires (see below picture) and I want to go & get the 275's all around.
After searching a bunch of posts on this forum, I still have a couple of questions:

1. Will the 275's fit without rubbing at all 4 corners?
2. Why is everybody here getting the 275/40R20 and not the 275/45R20? The stock tires are just fine on 45, so is there any reason to not go with the 45 on the 275's? WIll they rub on the 45?

Thanks in advance for your answer.
 

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The diameter of a stock 245/45-20 tire is 28.68 inches and the revs per mile is 725.22.

When you are buying a larger width replacement tire, you want to try to match these numbers to keep your speedometer accurate.

A 275/45-20 tire will have a larger diameter of 29.74 inches and the revs will be 699.30. This will make your speedometer read slow by 3.71%. A better choice would be the 275/40-20 tire. Its diameter is nearly identical to the 245 tire, at 28.66 inches. Also, the revs are 725.71. In this case, the speedometer will read slightly fast by only 0.07%.

Check out this tire size calculator:

http://www.1010tires.com/Tools/Tire-Size-Calculator/245-45R20/275-45R20/275-40R20?ismetric=False
 

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Fitment is not an issue. When I went the 270 route there were a lot more choices in the 40 then 45 series locally.
 

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2009 Challenger R/T
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The 40 and 45 number you are referencing is the aspect ratio. This number should not be used alone to determine the height of a tire, the height of a tire is based off both the aspect ratio and tire width. This is why a 245/45 and a 275/40 are nearly identical in height.

(245 x 0.45 = 110.25mm ; 275 x 0.40 = 110mm)
 

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Discussion Starter #5
Great info, thank you.
It looks like the 270/40-20 is the way to go then.

So again - no fitment issues with the 275s, no rubbing when turning, or in the rear over bumps, etc.?
 

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Discounttiredirect has a feature that lists optional sizes that "fit". I clicked on 265/45-20 and those listed were $202/ea and UP. Ninety (94) options pop up on 275/40-20 starting at $95/ea.

245/45-20
235/45-20
255/45-20
265/45-20
255/35-20
235/40-20
245/40-20
255/40-20
 

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Discussion Starter #7
Thank you.
The R/T is at the shop as we speak and 275 Falkens are been installed.
Can't wait!
 

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‘15 R/T 6M STP
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I like it.

Were the WRTs original to the car, or added later?
 

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‘15 R/T 6M STP
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Did you buy it new like that? Or used?

Thanks!
 

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tire size

with those 9 inch rims you can go 315 in the rear with no rubbing and good contact patch...but 275 is the largest for the front. I went with 275/40 all around...Conti Extreme Contact Sport....lovin' them...supper grippy.

tiresize.jpeg
 

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Discussion Starter #14
Did you buy it new like that? Or used?

Thanks!
Bought it like this new, this past weekend.
The rims are a factory option that I had to paid extra for.
It took me a while to find the right color and other options I wanted with this rims. But I think is worth it.
 

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How is it driving now any rubbing issues or anything i order 275/40/20 and wheel are same as yours 20x9 factorys really need make sure no issue in rubbing please let me know!
 

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Minimum recommended for a 315/35 would be 10.5"

A Guy
 

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Here are three photos of my new Cooper Zeon RS3-G1 275/40-20 tires mounted on my 9" Alcoa forged aluminum wheels. They look and handle great on my SRT and were not that expensive.
Looks great and thanks for the info a few months back. Will be installing my Zeon's in about another month. They have been in my garage for a few months since I still have some meat on my Atturo 800s. I got a bit over 30k miles on them and still have about 3/32 so can't complain about them but looking forward to a more performance tire.
 

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^^^Those look pretty all-seasony, I hope they perform they way you want them to.
 
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