$800 Flat Tire???
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Senior User
Joined: Jul 2006
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$800 Flat Tire???
My wife drives a 2005 AWD Escape Limited. She loves it. Last week she picked up a drywall screw in the sidewall of a tire. It couldn't be repaired. I was told by the Les Schwab guys that I had to replace all 4 tires as the SUV is AWD. The Continentals were about 70% gone. Evidently replacing just one or even two could somehow mess up the AWD. On the plus side, I did get rid of those noisy Continental tires. Anyone else hear of this or was I told a story?
Laughing Gas
Joined: Apr 2004
Posts: 819
Likes: 2
From: Northern Maine
I think they saw you coming. As long as the replacement tire is the same size you should have no problems. I guess that I wouldn't match an all season or summer tread with an aggressive snow tire or a bargain brand with a name brand either. With 70% worn tires, I would probably have bought one set and put the new ones on the front, got the last of the miles out of the old ones and then get another set. When your done, you would have good tires on your ride and one serviceable spare tire in case you pick up another dry wall screw. Anyway, you have four new ones now and peace of mind.
Postmaster
Joined: May 2003
Posts: 3,310
Likes: 9
From: E.Lincoln County, NC
I've read in several technical bulletins that combining new & heavily worn tires on an AWD vehicle can lead to the overheating and failure of the power transfer unit. Unequal diameter tires fool it into thinking there is slippage therefore applying power to the rear. Short distances of this doesn't overheat/harm the PT unit but prolonged operation will. IMHO if you had tires that were 70% worn then you aren't out much by having them replaced, certainly less than PTU repairs would be!
Thread Starter
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Senior User
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I've read in several technical bulletins that combining new & heavily worn tires on an AWD vehicle can lead to the overheating and failure of the power transfer unit. Unequal diameter tires fool it into thinking there is slippage therefore applying power to the rear. Short distances of this doesn't overheat/harm the PT unit but prolonged operation will. IMHO if you had tires that were 70% worn then you aren't out much by having them replaced, certainly less than PTU repairs would be!
Greg
Postmaster
Joined: May 2003
Posts: 3,310
Likes: 9
From: E.Lincoln County, NC
Well, you know how hunting for something specific always seems to disappear 
... This beats all around the bush but doesn't spell out what we're discussing.
From the Ford manual diagnostic section:
Symptom: The transfer case makes noise
Possible causes: Tire inflation pressure.
Tire and wheel size.
Action: MAKE SURE all tires and wheels are the same size and brand, and the inflation pressures are correct.
Tire inflation as well as size can affect diameter.
TIRE/AXLE OUT OF ACCEPTABLE RANGE
NOTICE: This test must be carried out on a hard surface in a vacant area without traffic.
NOTE: Conduct steps 1-7 outlined in Inspection and Verification prior to performing this test.
Test Step Result / Action to Take
J1 CHECK THE RECENT TIRE USAGE
Check with customer about recent tire usage or installation.
Has a tire been installed on the vehicle recently that was not originally supplied with the vehicle?
Yes
INFORM the customer to only use tires of the type supplied with the vehicle. CLEAR the DTCs. REPEAT the self-test.
No
GO to J2.
J2 CHECK TIRE SIZE AND BRAND
Check the tire size and the brand of tire.
Are all four tires the same size and brand?
Yes
GO to J3.
No
INSTALL tires that are the same size and brand. INFORM the customer to only use the same size tires and brand. CLEAR the DTCs. REPEAT the self-test.
J3 CHECK TIRE PRESSURES
Check the tire pressure in all 4 tires.
Are all 4 tires at the recommended tire pressure?
Yes
GO to J4.
No
ADJUST the tire pressures. CLEAR the DTCs. REPEAT the self-test. INFORM the customer to maintain the proper tire pressure.
The Escape system does have a safeguard to prevent/warn of overheating the PTU.
Heat Protection Mode
During very extreme off-road operation, the 4WD system has a heat protection system to protect the active torque coupling from damage. If the system detects an overheat condition, it enters a locked mode and turns on the 4WD indicator light in the instrument cluster. If the heat in the system continues to rise once in the locked mode, the 4WD control module disables the active torque coupling and causes the 4WD indicator light to flash continuously.
4WD Indicator Light
4WD — Illuminates continuously when the 4WD system is locked in 4WD due to its heat protection mode. In the locked mode, the vehicle resists turning and binds up when driven on dry pavement. To exit the locked mode, stop the vehicle and allow it to cool for 5 minutes with the engine running. When the 4WD indicator turns OFF, normal 4WD system function is restored.
4WD — Blinks continuously when the 4WD system is disabled due to its heat protection mode. To exit the disabled mode, stop the vehicle and allow it to cool for 5 minutes with the engine running. When the indicator turns OFF, normal 4WD system function is restored.
4WD — Blinks 3, 6, 8 or 10 times every minute when the 4WD system requires service. Use a scan tool to check for diagnostic trouble codes (DTCs). Refer to the Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index in this section.
Blinks Cause
3 Cluster is not receiving the 4WD indicator message from the 4WD control module
6 Invalid throttle position data received from the PCM
8 Invalid wheel speed data received from the ABS module
10 Active torque coupling circuit fault
4WD Messages in Message Center
SERVICE 4WD — Displayed when the 4WD system requires service. Use a scan tool to check for DTCs. Refer to the Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index in this section.
4WD LOCKED TEMPORARILY — Displayed when the 4WD system is locked due to heat protection. In the locked mode the vehicle resists turning and binds up when driven on dry pavement. To exit the locked mode, stop the vehicle with the engine running and allow it to cool for 5 minutes.
Driving the vehicle in this mode will not damage the 4WD system. The system can return to normal mode without stopping the vehicle if driving conditions allow.
4WD DISABLED TEMPORARILY — Displayed when the 4WD system is disengaged due to heat protection. To exit the disabled mode, stop the vehicle with the engine running and allow it to cool. Driving the vehicle in this mode will not damage the 4WD system. This will change how the vehicle handles in off-road, snowy or wet conditions.
4WD AUTO RESTORED — Displayed when normal 4WD system function is restored after a heat protection system occurrence.
... This beats all around the bush but doesn't spell out what we're discussing.From the Ford manual diagnostic section:
Symptom: The transfer case makes noise
Possible causes: Tire inflation pressure.
Tire and wheel size.
Action: MAKE SURE all tires and wheels are the same size and brand, and the inflation pressures are correct.
Tire inflation as well as size can affect diameter.
TIRE/AXLE OUT OF ACCEPTABLE RANGE
NOTICE: This test must be carried out on a hard surface in a vacant area without traffic.
NOTE: Conduct steps 1-7 outlined in Inspection and Verification prior to performing this test.
Test Step Result / Action to Take
J1 CHECK THE RECENT TIRE USAGE
Check with customer about recent tire usage or installation.
Has a tire been installed on the vehicle recently that was not originally supplied with the vehicle?
Yes
INFORM the customer to only use tires of the type supplied with the vehicle. CLEAR the DTCs. REPEAT the self-test.
No
GO to J2.
J2 CHECK TIRE SIZE AND BRAND
Check the tire size and the brand of tire.
Are all four tires the same size and brand?
Yes
GO to J3.
No
INSTALL tires that are the same size and brand. INFORM the customer to only use the same size tires and brand. CLEAR the DTCs. REPEAT the self-test.
J3 CHECK TIRE PRESSURES
Check the tire pressure in all 4 tires.
Are all 4 tires at the recommended tire pressure?
Yes
GO to J4.
No
ADJUST the tire pressures. CLEAR the DTCs. REPEAT the self-test. INFORM the customer to maintain the proper tire pressure.
The Escape system does have a safeguard to prevent/warn of overheating the PTU.
Heat Protection Mode
During very extreme off-road operation, the 4WD system has a heat protection system to protect the active torque coupling from damage. If the system detects an overheat condition, it enters a locked mode and turns on the 4WD indicator light in the instrument cluster. If the heat in the system continues to rise once in the locked mode, the 4WD control module disables the active torque coupling and causes the 4WD indicator light to flash continuously.
4WD Indicator Light
4WD — Illuminates continuously when the 4WD system is locked in 4WD due to its heat protection mode. In the locked mode, the vehicle resists turning and binds up when driven on dry pavement. To exit the locked mode, stop the vehicle and allow it to cool for 5 minutes with the engine running. When the 4WD indicator turns OFF, normal 4WD system function is restored.
4WD — Blinks continuously when the 4WD system is disabled due to its heat protection mode. To exit the disabled mode, stop the vehicle and allow it to cool for 5 minutes with the engine running. When the indicator turns OFF, normal 4WD system function is restored.
4WD — Blinks 3, 6, 8 or 10 times every minute when the 4WD system requires service. Use a scan tool to check for diagnostic trouble codes (DTCs). Refer to the Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index in this section.
Blinks Cause
3 Cluster is not receiving the 4WD indicator message from the 4WD control module
6 Invalid throttle position data received from the PCM
8 Invalid wheel speed data received from the ABS module
10 Active torque coupling circuit fault
4WD Messages in Message Center
SERVICE 4WD — Displayed when the 4WD system requires service. Use a scan tool to check for DTCs. Refer to the Four-Wheel Drive (4WD) Control Module Diagnostic Trouble Code (DTC) Index in this section.
4WD LOCKED TEMPORARILY — Displayed when the 4WD system is locked due to heat protection. In the locked mode the vehicle resists turning and binds up when driven on dry pavement. To exit the locked mode, stop the vehicle with the engine running and allow it to cool for 5 minutes.
Driving the vehicle in this mode will not damage the 4WD system. The system can return to normal mode without stopping the vehicle if driving conditions allow.
4WD DISABLED TEMPORARILY — Displayed when the 4WD system is disengaged due to heat protection. To exit the disabled mode, stop the vehicle with the engine running and allow it to cool. Driving the vehicle in this mode will not damage the 4WD system. This will change how the vehicle handles in off-road, snowy or wet conditions.
4WD AUTO RESTORED — Displayed when normal 4WD system function is restored after a heat protection system occurrence.
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Postmaster
Joined: May 2003
Posts: 3,310
Likes: 9
From: E.Lincoln County, NC
Not the TSB I was hunting but this spells it out........and he's not a tire dealer.
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Brett Foote
Elder User
Joined: Jan 2006
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Likes: 0
Its legit. I ruined a tire on my new '09 AWD with 6,000 miles on it and the dealer spent a lot of time determining my 3 remaining tires were within certain specs before agreeing to order 1 new Michelin (at $170 per). Needless to say I was very concerned because I had heard of this before on Car Talk with Click and Clack when a listener borrowed a friend's Subaru, hit a pothole, and subsequently had to replace all 4 tires.
Posting Guru
Joined: Feb 2002
Posts: 1,534
Likes: 2
From: Warren, MI
If all that info on a 4WD heat lock up condition isn't for a Escape, what's it for?
Postmaster
Joined: May 2003
Posts: 3,310
Likes: 9
From: E.Lincoln County, NC
It IS for an Escape, from the 2005 service manual..............
Similar to Fords Fail Safe Cooling mode. It shuts out cylinders until it cools down but it's an emergency feature not to replace proper maintenance/repair/operation.
Similar to Fords Fail Safe Cooling mode. It shuts out cylinders until it cools down but it's an emergency feature not to replace proper maintenance/repair/operation.
Thread Starter
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Senior User
Joined: Jul 2006
Posts: 268
Likes: 1
Thank you so much for providing the documentation. I now feel much better. The original Continentals weren't my choice as they were very noisy at freeway speeds. I guess it is better than having to replace tires that are only 40% gone. I was fairly religious about tire rotation and inflation but only because I always rotated and checked my tire pressure even before I had AWD. I will make sure not to abandon this good habit especially now that I know what it could cost me in the future. You rock!
Greg
Greg
Logistics Pro
Joined: Jul 2006
Posts: 4,512
Likes: 18
From: Detroit
Agree on the size thing...you could shave a new tire...
I agree that 4WD systems are sensitive to tire size differences. Subaru says that all four tires must be within 1/4" in circumference (not diameter).
If you have to replace one tire in a newer set, you might be able to find a tire dealer that deals with race and autocross applications and have them shave down a new tire to 50% tread depth or whatever you need.
Seems like a waste but it salvages three other tires.
George
If you have to replace one tire in a newer set, you might be able to find a tire dealer that deals with race and autocross applications and have them shave down a new tire to 50% tread depth or whatever you need.
Seems like a waste but it salvages three other tires.
George