19's front - 20's rear ...?

[Ken H.]

There may be a way to re-align that camera as on modern cars with cameras, if you have a windshield replaced, they need to do a high-dollar recalibration to make sure everything aligns with the new glass. You might try asking a windshield replacement business about it to see if there is any flexibility with that process.

I asked Ford that. They said no.

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[Ken H.]

Pirelli Trofeo RS 305/30/19 - 26.6”
Michelin PS4 AS 285/35/20 - 27.9”
285/30/20 - 26.8”
275/35/20 - 27.8”
275/30/20 - 26.5”

Pirelli Trofeo RS 315/30/19 - 26.5”
Michelin PS4 AS 305/35/20 -28.4”
305/30/20 - 27.2
295/35/20 - 28.1”
295/30/20 - 27”

 

[DevilDog]

Now I'm thinking maybe I should just leave well enough alone and lower it a little to change the stance.

 

[Dave2013M3]

I’m one of those experiencing electronic problems due to wheel/ tire changes. I went with 20x10 285/35/20 front & 20x11 305/35/20 rear. I lost my pre-collision assist & both types of cruise control. Ford said it was due to larger diameter tires in front affecting the windshield camera that views the road & provides data for the computer. Switched back to stock DH HP 19” setup & problem resolved. Ran all summer & Fall. When cold weather came, put 20’s back on with 285/30/20 fronts (almost same diameter as stock 19’s). Problem back. I haven’t taken it in yet. Not sure if I have to go to 275’s front, or change rears to 295’s with similar diameter to stock 19’s to lower the rear. Also, another person had lost pre-collision & cruise without changing wheels/tires & it turned out to be a wheel sensor.
All I know is that I wish I had just stuck with the original 19’s even if it meant having to go with “skinnier” all season tires. BEWARE.

You have to try to keep the diameter within .3-.5" from OEM. The car doesn't see wheel diameter, it sees over all diameter.

 

[Ken H.]

You have to try to keep the diameter within .3-.5" from OEM. The car doesn't see wheel diameter, it sees over all diameter.

My new fronts are 0.2” taller. I thought that would solve the problem. Rears are still taller by 1.9”. Could that be the problem?

 

[Ken H.]

You have to try to keep the diameter within .3-.5" from OEM. The car doesn't see wheel diameter, it sees over all diameter.

In addition, I’m using Tire diameter for my comparisons. So wheel diameter is incorporated into those numbers. I realize that the car dot see wheel diameter.

 

[Ken H.]

One last thing & I’ll shut up. I don’t know why there aren’t lots of us having this problem. There are many entries about changing wheels & tires. Why do I seem to be the only one. What’s up with that?

 

[Sofa King]

One last thing & I’ll shut up. I don’t know why there aren’t lots of us having this problem. There are many entries about changing wheels & tires. Why do I seem to be the only one. What’s up with that?

Yeah, what makes you so special?... lol

It appears that lowering doesn't necessarily cause issues, as I haven't seen anyone reporting such. I think you need to go smaller in the rear too... 30 series instead of 35 (f&r) as that would be closer to the trofeos... though I am sure I have seen others running same size (35 series). Perhaps because stock tires are smaller from factory with the HP?

 

[robvas]

Past SVT Cobras ran staggered not only front and rear in diameter

What years was this?

 

[Dave2013M3]

What years was this?

I believe 2013 and 2014

 

[Dave2013M3]

My new fronts are 0.2” taller. I thought that would solve the problem. Rears are still taller by 1.9”. Could that be the problem?

You need to move to a 30 series rear tire.

 

[Dave2013M3]

Thanks. Gorgeous M2.

Thanks!!!

 

[robvas]

I believe 2013 and 2014

you said Cobra not GT500

 

[Garcia172]

I bet it's the GPS speed measurement and the tire circumference that don't jive resulting in the loss of the cruise control and crash avoidance. Some people here said you could compensate using Forscan as you can enter in the tire circumference but I don't have Forscan and am not aware (like how would I be lol) of anyone that's tried to compensate this way.

 

[JimiHendrix]

Sticking with 19's on all 4 corners
changing the wheels to SVE forged 19's - 19X10.5 front - 19x11 rear with a 325/30/19 (maybe: Hoosier Track Attack Pro) in the rear and keeping the stock 305/30/19 in front

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