"AWD OFF" Light

[Gray Brick]

AWD Off did not turn on again on a return trip of 60 miles.

Spirited driving from 0-80 MPH.

[Brucelinc]

With that much difference in tire sizes, you are playing with fire.  Maybe you will not get burned....today...or tomorrow.....but you likely will at some point.

[AJP turbo]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

[ZSHO]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

[AJP turbo]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

No track

[ZSHO]

Bruce how did you measure your 0-60 in your sig?

Side note: when i drag race pretty much everytime at the end i get "service advance trac " indicator. I restart the car and its fine...ive gone 150mph in the car before and its fine....i think its from brake boosting at the launch that it doesnt like....at the strip is the only time i brake boost

AJ Doing 150mph how long is the Track.?  BTW Please be safe.  Z

No track

I would advise caution but you already know that,please be safe my friend.  Z

[Brucelinc]

I have measured 0-60 2 ways.  Using my Aeroforce gauge, I consistently get 3.99 - 4.09.  The number in my sig is from using the Wallace racing calculator.  It bases 0-60 off 1/8 mile time and speed.  Since that number is in the range I see with the gauge, I feel pretty comfortable using it.

I have never had the advance track light come on at the track.  The only time I have ever seen it was when I was deliberately trying to powerslide around on a snowy parking lot.

I am probably a wimp when it comes to brake boosting.  I don't even start until the first yellow light comes on and then only to around 1800 so it is very short and mild.

[AJP turbo]

Could be mars for all you know...i could say exactly where and when i did it on a public street...wont hold water if authorities tried to use it as evidence....how would you know i wasnt lying about it?...even if i video recorded it....maybe i flashed the ecu with a really large number for the circumference of the tire scalar making the speedo way off?

I dont think many of the you tube charges stand up...internet gossip

Had a coworker tell me a cop looked at the max speed in his gps ...when u touch the speed box it shows max speed....mine was from the drag strip so if thats true it would be dumb for a cop to use that

[Gray Brick]

If we are looking at % difference this is what I calculated:

Calculated 2 ways...

--Circumference--
Speedo Error:
Diameter   728mm   744mm
Circumference   2287.1mm   2337.3mm
Poke   82.7mm   82.7mm
Inset   158.7mm   158.7mm
Speedo error   0%   -2.15%
Reading at 30mph   30mph   29.35mph
Reading at 60mph   60mph   58.71mph
Ride height gain   0mm   8mm
Arch gap loss   0mm   8mm

--Revs/Mile--

275/40-20: 706/mi
296/40-20: 690/mi
706/690 = 1.0232 = 2.32%


Both of these calculations are under the 3% recommended between front to back.


Any other suggestions for this calculation?



Tire Size   275/40R20
mm   inches
Tire
Width   275   10.83
Aspect
Ratio   40   -
Rim
Diameter   508   20.00
Sidewall
Height   110   4.33
Tire
Diameter   728   28.66
Circum-
ference   2286   90.00
Revolutions   437/km   706/m

Tire Size   295/40R20
mm   inches
Tire
Width   295   11.61
Aspect
Ratio   40   -
Rim
Diameter   508   20.00
Sidewall
Height   118   4.65
Tire
Diameter   744   29.29
Circum-
ference   2336   91.97
Revolutions   428/km   690/mi

[ZSHO]

We will always promote the safety related aspects of driving in this Fine Forum,please lets stick to the Topic posted by the OP,thanks.  Z   

[Blackhawk]

We've now seen 3 different numbers for calculations.  I still think it's pretty safe to say it's coming the tire height differences being that's the only recent change you have made..  I'd bring it to the dealer and let them weigh in but I am fairly certain they will say the tires are the issue the second they figure out the height differences.

If we are looking at % difference this is what I calculated:

Calculated 2 ways...

--Circumference--
Speedo Error:
Diameter   728mm   744mm
Circumference   2287.1mm   2337.3mm
Poke   82.7mm   82.7mm
Inset   158.7mm   158.7mm
Speedo error   0%   -2.15%
Reading at 30mph   30mph   29.35mph
Reading at 60mph   60mph   58.71mph
Ride height gain   0mm   8mm
Arch gap loss   0mm   8mm

--Revs/Mile--

275/40-20: 706/mi
296/40-20: 690/mi
706/690 = 1.0232 = 2.32%


Both of these calculations are under the 3% recommended between front to back.


Any other suggestions for this calculation?



Tire Size   275/40R20
mm   inches
Tire
Width   275   10.83
Aspect
Ratio   40   -
Rim
Diameter   508   20.00
Sidewall
Height   110   4.33
Tire
Diameter   728   28.66
Circum-
ference   2286   90.00
Revolutions   437/km   706/m

Tire Size   295/40R20
mm   inches
Tire
Width   295   11.61
Aspect
Ratio   40   -
Rim
Diameter   508   20.00
Sidewall
Height   118   4.65
Tire
Diameter   744   29.29
Circum-
ference   2336   91.97
Revolutions   428/km   690/mi

[Gray Brick]

Does anyone have the official statement on what is acceptable from Ford on the difference on size from the front/back tires?

Thank you.

[AJP turbo]

Does anyone have the official statement on what is acceptable from Ford on the difference on size from the front/back tires?

Thank you.

I would say the official statement is the size listed on the door tag....even though a staggered size has been done before and people have not had problems , i cant see ford saying that any amount of difference would be without consequence

[Brucelinc]

I have never heard the difference stated as a percentage.   It is common to warn that if all tires are the same brand and size, a difference in tread depth of more than 3/32 is unacceptable. 

[pmezo33]

I have never heard the difference stated as a percentage.   It is common to warn that if all tires are the same brand and size, a difference in tread depth of more than 3/32 is unacceptable.

That's always been my understanding too.  With AWD, I always go same size all around.