Mounted Run Flats on CTT
10-12-2007, 12:19 AM
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Mounted Run Flats on CTT
Just bought tires for My Wife's CTT. Went with the Bridgestone Dueler HP RFT (Run Flat) model. Size 285/45/19 . Very happy with them. Cost about 1150$ . Just FYI if anyone else wants the runflat option for the peace of mind on the family cruiser.
10-12-2007, 03:06 AM
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When I first bought my Touareg I thought Run-Flats would be a good idea. Of course, my lowly Touareg is not a Porsche Cayenne, but let's just agree that the AWD systems in the Touareg and the Cayenne are more than just "similar," OK?
Tire requirements for the Touareg/Cayenne are pretty specific. There is a lengthy portion in the Bentley Repair Manual for the Touareg about measuring the rolling circumfrence of all four tires to assure that they are all within 0.5" in circumfrence.
The reason for this tight circumfrence requirement is the ESP, ABS and differential positioning (stepper) motor(s) all rely on a "given" wheel/tire circumfrence to function properly.
What is the circumfrence of a Run-Flat tire when the main tire has deflated? A lot more than 0.5" less than the fully inflated tire.
If all you do is use the benefits of a Run-Flat to safely negotiate your way to the shoulder to replace your flat tire with the spare, then no harm, no foul.
The problem arises when you rely on the Run-Flat to travel longer distances, such as to the nearest service station, to have the spare tire fitted or the flat fixed. This prolonged driving with a failed tire could do severe damage to the AWD components in your vehicle. It has been suggested that turning OFF the ESP (PSM?) could alleviate some of this potential damage, it is still not a good idea.
This is why VW (and Porsche?) do not recommend any Run-Flat tires for use with the Touareg (Cayenne?).
If you have other information that supports the use of Run-Flat tires in the Touareg/Cayenne platform, I would be very interested to hear about it.
HTH
Tire requirements for the Touareg/Cayenne are pretty specific. There is a lengthy portion in the Bentley Repair Manual for the Touareg about measuring the rolling circumfrence of all four tires to assure that they are all within 0.5" in circumfrence.
The reason for this tight circumfrence requirement is the ESP, ABS and differential positioning (stepper) motor(s) all rely on a "given" wheel/tire circumfrence to function properly.
What is the circumfrence of a Run-Flat tire when the main tire has deflated? A lot more than 0.5" less than the fully inflated tire.
If all you do is use the benefits of a Run-Flat to safely negotiate your way to the shoulder to replace your flat tire with the spare, then no harm, no foul.
The problem arises when you rely on the Run-Flat to travel longer distances, such as to the nearest service station, to have the spare tire fitted or the flat fixed. This prolonged driving with a failed tire could do severe damage to the AWD components in your vehicle. It has been suggested that turning OFF the ESP (PSM?) could alleviate some of this potential damage, it is still not a good idea.
This is why VW (and Porsche?) do not recommend any Run-Flat tires for use with the Touareg (Cayenne?).
If you have other information that supports the use of Run-Flat tires in the Touareg/Cayenne platform, I would be very interested to hear about it.
HTH
10-12-2007, 07:22 AM
#3
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When I first bought my Touareg I thought Run-Flats would be a good idea. Of course, my lowly Touareg is not a Porsche Cayenne, but let's just agree that the AWD systems in the Touareg and the Cayenne are more than just "similar," OK?
Tire requirements for the Touareg/Cayenne are pretty specific. There is a lengthy portion in the Bentley Repair Manual for the Touareg about measuring the rolling circumfrence of all four tires to assure that they are all within 0.5" in circumfrence.
The reason for this tight circumfrence requirement is the ESP, ABS and differential positioning (stepper) motor(s) all rely on a "given" wheel/tire circumfrence to function properly.
What is the circumfrence of a Run-Flat tire when the main tire has deflated? A lot more than 0.5" less than the fully inflated tire.
If all you do is use the benefits of a Run-Flat to safely negotiate your way to the shoulder to replace your flat tire with the spare, then no harm, no foul.
The problem arises when you rely on the Run-Flat to travel longer distances, such as to the nearest service station, to have the spare tire fitted or the flat fixed. This prolonged driving with a failed tire could do severe damage to the AWD components in your vehicle. It has been suggested that turning OFF the ESP (PSM?) could alleviate some of this potential damage, it is still not a good idea.
This is why VW (and Porsche?) do not recommend any Run-Flat tires for use with the Touareg (Cayenne?).
If you have other information that supports the use of Run-Flat tires in the Touareg/Cayenne platform, I would be very interested to hear about it.
HTH
Tire requirements for the Touareg/Cayenne are pretty specific. There is a lengthy portion in the Bentley Repair Manual for the Touareg about measuring the rolling circumfrence of all four tires to assure that they are all within 0.5" in circumfrence.
The reason for this tight circumfrence requirement is the ESP, ABS and differential positioning (stepper) motor(s) all rely on a "given" wheel/tire circumfrence to function properly.
What is the circumfrence of a Run-Flat tire when the main tire has deflated? A lot more than 0.5" less than the fully inflated tire.
If all you do is use the benefits of a Run-Flat to safely negotiate your way to the shoulder to replace your flat tire with the spare, then no harm, no foul.
The problem arises when you rely on the Run-Flat to travel longer distances, such as to the nearest service station, to have the spare tire fitted or the flat fixed. This prolonged driving with a failed tire could do severe damage to the AWD components in your vehicle. It has been suggested that turning OFF the ESP (PSM?) could alleviate some of this potential damage, it is still not a good idea.
This is why VW (and Porsche?) do not recommend any Run-Flat tires for use with the Touareg (Cayenne?).
If you have other information that supports the use of Run-Flat tires in the Touareg/Cayenne platform, I would be very interested to hear about it.
HTH
My Family is trained to use the vehicle as a tool. My wife for example prior to the RFT knows that the car is just there to save her life and the lives of others. If she had a flat before, she knows to drive on the rim, or all 4 rims if need be until she got to an area of safety/service. I race and inistruct and all the cars we have are meant to be used to their full potential if need be, whether they are street or race applications. That being said, my relationship with Porsche gives me a great deal of comfort that the adaptive nature built into the Cayenne/Tourag would more than compensate for the differences in rolling radius for quite sometime, certainly long enough for her to get to safety.
10-12-2007, 10:30 AM
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10-12-2007, 11:46 PM
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http://www.dunloptires.com/dunlop/si...ctratio=55&x=1
I could be wrong and have fired off an email to Tirerack, but I am checking.
The weird thing is that they also have the Dunlop Grandtrek WT M2, but in a 235/60/18, which is not a runflat... but they don't have the M2 on the 255/55/18...
10-13-2007, 12:10 AM
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OK, if you say so, but someone should tell Porsche that the Cayenne is 65%/85% common parts/labor with the Touareg......
10-13-2007, 01:02 AM
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I just looked at the Porsche approved tire list and they have Dunlop Grandtrek WT M3's on the list in 255/55/18 on the list. According to Dunlop site, they only come in run flat.
http://www.dunloptires.com/dunlop/si...ctratio=55&x=1
I could be wrong and have fired off an email to Tirerack, but I am checking.
The weird thing is that they also have the Dunlop Grandtrek WT M2, but in a 235/60/18, which is not a runflat... but they don't have the M2 on the 255/55/18...
http://www.dunloptires.com/dunlop/si...ctratio=55&x=1
I could be wrong and have fired off an email to Tirerack, but I am checking.
The weird thing is that they also have the Dunlop Grandtrek WT M2, but in a 235/60/18, which is not a runflat... but they don't have the M2 on the 255/55/18...
Any chance you could post the "Porsche approved tire list" you mention?
TIA
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10-13-2007, 09:34 AM
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10-13-2007, 01:09 PM
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