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Rear tire size

A.alansari

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Hi

Got new wheels i was searching for tires around here i have found

front 275-35-20
Rear 315-35-20



There is no 305-35-20 around here for the rear so if go with 315 is there going to be issues with the car computers since it is bigger than 3% than the original

I don't want to get less than the original because there will be bigger gap in the wheel well and i don't want to lower the car

the original tire is 275-40-19
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I was thinking about switching to 20" wheels, but it sounds like some people have had issues with cruise control, etc. I'm currently running 285/30/19's in the front and 325/35/19's in the rear on aftermarket wheels. If I switched to 20's, I'd probably go with a 315 tire in rear. I think a 325 might be a little too wide.
 

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I was thinking about switching to 20" wheels, but it sounds like some people have had issues with cruise control, etc.
How so? Your car doesn't know what size wheels are on it.
 

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It's my understanding that the computer knows the difference between 19" and 20" wheels. I could be wrong.
 
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A.alansari

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I was thinking about switching to 20" wheels, but it sounds like some people have had issues with cruise control, etc. I'm currently running 285/30/19's in the front and 325/35/19's in the rear on aftermarket wheels. If I switched to 20's, I'd probably go with a 315 tire in rear. I think a 325 might be a little too wide.
315-35-20 is 28.7" diameter
325-35-19 is 28" so yours is close to stock diameter thats why you didn't have issues with it stock is 27.7"

And yes i'm asking because i've seen the posts about the cruise control and wanted to make sure before buying if anyone have the same setup without issues
 


DevilDog

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315-35-20 is 28.7" diameter
325-35-19 is 28" so yours is close to stock diameter thats why you didn't have issues with it stock is 27.7"

And yes i'm asking because i've seen the posts about the cruise control and wanted to make sure before buying if anyone have the same setup without issues
The only reason I'd switch to a 315-width tire in the rear is because I'd be concerned about rubbing with 20" wheels. My 325's are pretty much flush with my rear fender. The 315 is about 1/2" narrower. As I said, I'd be concerned about throwing the computer off in some way. I'm not a wheel or tire expert by any stretch of the imagination. Just my personal thoughts.
 

ChitownStang

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I did 285/35 x 315/35 on my new 20's with Conti DWS Sports
No Rubbing , speedo off 3mph but who cares
I think my cruise control may not work anymore come to think of it, didn't realize it was the tires.
I'll have my stock summers back on in a couple months so I will need to test

S650 Mustang Rear tire size IMG_6490
 
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A.alansari

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I did 285/35 x 315/35 on my new 20's with Conti DWS Sports
No Rubbing , speedo off 3mph but who cares
I think my cruise control may not work anymore come to think of it, didn't realize it was the tires.
I'll have my stock summers back on in a couple months so I will need to test

IMG_6490.webp
so most likely the cruise control won't work with this setup ?

and your wheels looks so good on the white color
 

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It's my understanding that the computer knows the difference between 19" and 20" wheels. I could be wrong.
As I understand it, the ECU/BCM is comparing wheel revs with engine revs and speed, also difference between wheels, not the actual wheel size. Keep the revs per mile within tolerance and all should work fine.
Sorry, but I don't know what the tolerance is, but it has to be enough to account for tyre wear which is normally about 7 - 8mm radius
 

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Hi

Got new wheels i was searching for tires around here i have found

front 275-35-20
Rear 315-35-20

There is no 305-35-20 around here for the rear so if go with 315 is there going to be issues with the car computers since it is bigger than 3% than the original

I don't want to get less than the original because there will be bigger gap in the wheel well and i don't want to lower the car

the original tire is 275-40-19
As most have mentioned, should be fine. What 20" wheels did you get? I went with the same setup by the way (just 285 front instead of 275) because it looks so good and I don't want to lower the car either.
 
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A.alansari

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As most have mentioned, should be fine. What 20" wheels did you get? I went with the same setup by the way (just 285 front instead of 275) because it looks so good and I don't want to lower the car either.
custom wheels like the super snake 2026

S650 Mustang Rear tire size IMG_4464
S650 Mustang Rear tire size IMG_4462
 

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front 275-35-20
Rear 315-35-20



There is no 305-35-20 around here for the rear so if go with 315 is there going to be issues with the car computers since it is bigger than 3% than the original
Is there no 30 aspect ratio available, 315/30, instead of 35?
 

exm

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^ Those look fantastic!
 
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A.alansari

A.alansari

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Is there no 30 aspect ratio available, 315/30, instead of 35?
there is but the overall diameter will be smaller than stock which will look ugly because it will have bigger wheel well gap
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