Rear tire size

[Westphal]

When I purchase a forged (not flow formed) set of wheels from Apex for the track at 11" apiece, I will purchase all four in the rear offset only. Then I will install a spacer on the front to make up the difference. Then all four wheels may be swapped around without removing the tires.

I'm doing the same thing with my GTO, fitting 18X9 wheels all around with about 15mm spacer at the front and possibly none at the rear. GTOs had plenty of clearance at the rear to the inside with an 18X8 and can have some to the outside if the fender lips are rolled. I installed coilovers for my clearance up front as there wasn't much with the 18X8 wheels and there's some room to go out.

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[ChitownStang]

Does cruise control completely not work? Or is it just the adaptive and/or lane keep assist?

So I dove on the interstate today and tried to set cruise control, set it to speed and it went green , would not engage pedal.
Tried adaptive cruise and that said it wasn’t available.
So either it the bigger diameter tires or my cpu is messed up:
Luckily I never use cruise control! lol

 

[Junkyard Dog]

So I dove on the interstate today and tried to set cruise control, set it to speed and it went green , would not engage pedal.
Tried adaptive cruise and that said it wasn’t available.
So either it the bigger diameter tires or my cpu is messed up:
Luckily I never use cruise control! lol

If it wasn't for cruise control, I would surely lose my license due to speeding violations.

 

[Ken H.]

So I dove on the interstate today and tried to set cruise control, set it to speed and it went green , would not engage pedal.
Tried adaptive cruise and that said it wasn’t available.
So either it the bigger diameter tires or my cpu is messed up:
Luckily I never use cruise control! lol

Hope I don’t sound like a broken record, BUT, Same for me. Ford dealer replaced my CCM (Cruise Control Module) but didn’t fix it. After consulting with Ford big fogs, told me it was the taller front tires changing the angle that the windshield camera had with the road, affecting the data inputs to the computer. Also, the Adaptive CC uses that data. If you have Adaptive CC, can’t switch to Regular CC because it’s affected too.
Didn’t say it’s a circumference/revs per mile issue. Who knows at this point.

 

[A.alansari]

What company did you get them from?

From Alibaba

 

[ChitownStang]

Hope I don’t sound like a broken record, BUT, Same for me. Ford dealer replaced my CCM (Cruise Control Module) but didn’t fix it. After consulting with Ford big fogs, told me it was the taller front tires changing the angle that the windshield camera had with the road, affecting the data inputs to the computer. Also, the Adaptive CC uses that data. If you have Adaptive CC, can’t switch to Regular CC because it’s affected too.
Didn’t say it’s a circumference/revs per mile issue. Who knows at this point.

Interesting info Ken,
Isn’t complex technology on these cars great…. Not! lol

 

[MidwayJ]

I get that, so why do some people go squared? Is it purely a cost saving tactic so that they can rotate front and back tyres?

That's a big part of it. Another reason is to maximize traction up front. These cars have heavy front ends, so they need as much rubber as possible for hard cornering. That's why you often see 19x11 all the way around for track use.

 

[MidwayJ]

When I had the 20x10 wheels, they had a +35mm offset all around. So depends on the wheels I guess.

It's the width. 10 inches is the maximum you can run with the same offset front and rear. A wider wheel with +35 offset in back will poke outside the fender and in front will contact the strut on the inside.

 

[MidwayJ]

Hope I don’t sound like a broken record, BUT, Same for me. Ford dealer replaced my CCM (Cruise Control Module) but didn’t fix it. After consulting with Ford big fogs, told me it was the taller front tires changing the angle that the windshield camera had with the road, affecting the data inputs to the computer. Also, the Adaptive CC uses that data. If you have Adaptive CC, can’t switch to Regular CC because it’s affected too.
Didn’t say it’s a circumference/revs per mile issue. Who knows at this point.

This must be an S650 thing. I came from an S550 and don't recall seeing this issue discussed in the 6g forum.

I wonder what the threshold is for having problems. I currently have a GT performance pack with 27" diameter tires up front. The three front tire options I'm considering with aftermarket wheels are 27.6, 27.7, and 27.9 inches.

 

[Ken H.]

This must be an S650 thing. I came from an S550 and don't recall seeing this issue discussed in the 6g forum.

I wonder what the threshold is for having problems. I currently have a GT performance pack with 27" diameter tires up front. The three front tire options I'm considering with aftermarket wheels are 27.6, 27.7, and 27.9 inches.

The 26.6 & 26.7 are <3%
The 27.9 is >3%.
I’m hearing stay <3%, but my 2nd set are <3% & I still had problem recur. I’m at a loss for advice except to get as close to stock as possible even if it means getting smaller, narrower tires. And, I’m not sure if the rears matter also.

 

[MidwayJ]

The 26.6 & 26.7 are <3%
The 27.9 is >3%.
I’m hearing stay <3%, but my 2nd set are <3% & I still had problem recur. I’m at a loss for advice except to get as close to stock as possible even if it means getting smaller, narrower tires. And, I’m not sure if the rears matter also.

Staying as close to stock diameters as possible makes sense, but it's quite annoying for options to be so limited.

 

[A.alansari]

Staying as close to stock diameters as possible makes sense, but it's quite annoying for options to be so limited.

if i want to get like stock diameter i will have to get

front 295-30-20
Rear 325-30-20

and i don't think the front will fit

 

[ogieogelthorpe]

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

Velgen VF5 with Nitto NT555 tires: 275/35/20 front (20x10), 305/30/20 rear (20x11).
The rear tires stick out ever so slightly. Does it get stuff on the rear panel? Sure does. Do I regret doing this? Not for a second.
The 305/30/20 are essentially identical to the stock tire size, so speedometer isn't an issue at all. If you go with 35's you will be off a 3-4 MPH at 65 MPH (and off more at higher speeds) unless you get the computer updated.

 

[MidwayJ]

Velgen VF5 with Nitto NT555 tires: 275/35/20 front (20x10), 305/30/20 rear (20x11).
The rear tires stick out ever so slightly. Does it get stuff on the rear panel? Sure does. Do I regret doing this? Not for a second.
The 305/30/20 are essentially identical to the stock tire size, so speedometer isn't an issue at all. If you go with 35's you will be off a 3-4 MPH at 65 MPH (and off more at higher speeds) unless you get the computer updated.

"Stock" for the performance pack cars is 27.7 diameter in the rear, so 305/30 would be a little smaller. Also, the OP has previously expressed that he does not want a taller tire up front than the rear.

Those wheels are very nice!

 

[jdenis43]

Velgen VF5 with Nitto NT555 tires: 275/35/20 front (20x10), 305/30/20 rear (20x11).
The rear tires stick out ever so slightly. Does it get stuff on the rear panel? Sure does. Do I regret doing this? Not for a second.
The 305/30/20 are essentially identical to the stock tire size, so speedometer isn't an issue at all. If you go with 35's you will be off a 3-4 MPH at 65 MPH (and off more at higher speeds) unless you get the computer updated.

Your car looks great. I have a white 24 and I am looking at the same rims. Is your car lowered? You said it sticks out slightly. What rim offset do you hae?

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