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tire size mistake

joez3

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My wife has a 2015 LE, she got it new, this is her car and she takes care of it. About 6 months ago she needed to replace the rear tires, she when to the ford dealer where she brought the car, they put 2 new Michelins on. Last night she asked me to check under the car to see if she ran over something. Any way I noticed that the new tires are 255 40 r19, this car came with wider rims on the rear and 275 40 r19 tires.
So I got 2 questions:
Tech question, I know that the speedometer will be off, will this cause any other problems? She doesn't track the car.

Relationship question, should I say anything to her? This is her car and wants to take care of it her self.
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Monopoly

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id take it back. Get them to mount the proper size tires.
 

Torched10

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I'd c
My wife has a 2015 LE, she got it new, this is her car and she takes care of it. About 6 months ago she needed to replace the rear tires, she when to the ford dealer where she brought the car, they put 2 new Michelins on. Last night she asked me to check under the car to see if she ran over something. Any way I noticed that the new tires are 255 40 r19, this car came with wider rims on the rear and 275 40 r19 tires.
So I got 2 questions:
Tech question, I know that the speedometer will be off, will this cause any other problems? She doesn't track the car.

Relationship question, should I say anything to her? This is her car and wants to take care of it her self.
I'd call Michelin and see what they say,or call one if the bigger on line tire guys.i,put 305s on my Shelby,which came with 285 and it was fine.putting a smaller tire may be safety issue,less rubber surface to stop the car in emergency.
 

Cobra Jet

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My wife has a 2015 LE, she got it new, this is her car and she takes care of it. About 6 months ago she needed to replace the rear tires, she when to the ford dealer where she brought the car, they put 2 new Michelins on. Last night she asked me to check under the car to see if she ran over something. Any way I noticed that the new tires are 255 40 r19, this car came with wider rims on the rear and 275 40 r19 tires.
So I got 2 questions:
Tech question, I know that the speedometer will be off, will this cause any other problems? She doesn't track the car.

Relationship question, should I say anything to her? This is her car and wants to take care of it her self.

EDIT: correcting info

Here’s stock tire sizes for reference


From AM’s website:

27CCF11D-44E1-4B4F-8E1E-B4A3D2F1587F.webp
 
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joez3

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Just to clarify the car is a 2015 mustang 5.0 limited edition. Part of the limited edition package included the performance pack.
 

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ugstang17

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If you take the time to open the drivers side door and look at the tag for tire sizes and pressure it will tell you what came on that car factory. The only Mustang setup to come with a staggered setup to my knowledge in recent years is the 13/14 GT500. 07-09 had a staggered setup but on the size sizes rims. I am not familiar with 10-12 GT500 as I do not like those years in any model of Mustang.

Q: Why did she think she ran over something? Is that tire related or something non related that simply got you to looking at the tire size.

As for how to address it, you know her best. That's your call.
 

Cobra Jet

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Just to clarify the car is a 2015 mustang 5.0 limited edition. Part of the limited edition package included the performance pack.

Oops... sorry!

Will correct post.
 

lacanteen

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I agree with making the dealer fix it right.

My .02
 

Bikeman315

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id take it back. Get them to mount the proper size tires.
+1 So what does your invoice show? Did you pay for 275 tires? Regardless the dealer f-cked up. This is on them, not you or your wife. Unless, of course, they told your wife what they were doing and she agreed. You need to speak with her and get the whole story.
 

Brazos609

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Tech question, I know that the speedometer will be off, will this cause any other problems? She doesn't track the car. Relationship question, should I say anything to her? This is her car and wants to take care of it her self.
She didn't do anything wrong or make any mistake, the dealership did. She has just been driving a little slower than she thought she was for a while. Tell her you noticed the dealership put on the wrong tires. Go back to the dealership and tell them you want them to move those tires to the 9" front rims and give you a matching pair of the correct size 275/40R19 tires to go on the 9.5" rear rims at a substantial discount.
 

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Torched10

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I'd be careful with wife conversation,could be she asked for best price and 255 was less than 275.so she thought she'd save a few bucks.
 

Bikeman315

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I'd be careful with wife conversation,could be she asked for best price and 255 was less than 275.so she thought she'd save a few bucks.
Agreed, but the dealer should have never put that tire on that wheel. And I’m all for the wife taking care of things herself (my wife does to) but if she didn’t know the right answer it might have been prudent to ask.
 
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kent0464

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My wife has a 2015 LE, she got it new, this is her car and she takes care of it. About 6 months ago she needed to replace the rear tires, she when to the ford dealer where she brought the car, they put 2 new Michelins on. Last night she asked me to check under the car to see if she ran over something. Any way I noticed that the new tires are 255 40 r19, this car came with wider rims on the rear and 275 40 r19 tires.
So I got 2 questions:
Tech question, I know that the speedometer will be off, will this cause any other problems? She doesn't track the car.

Relationship question, should I say anything to her? This is her car and wants to take care of it her self.

The 255/40/19 have a diam. Of 27” and a side wall of 4”......the 275/40/19 have a diam. Of 27.7 and a side wall of 4.3”.
Is it dangerous-no
Will it have an impact on the speedo- probably not enough to even notice.
The only thing she might notice is the ride will be slightly rougher because of the smaller side wall.
Personally I’d take it back and raise hell until they replaced the tires with the proper size.
 
 








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