AWD Jeep...blow 1 tire, replace all 4
03-04-2009, 03:36 AM
#21
[QUOTE=Legal Bill,Mar 4 2009, 12:09 AM] Remeber folks, its not just me.
03-04-2009, 04:46 AM
#23
Originally Posted by boltonblue,Mar 4 2009, 07:31 AM
ah bill you are confusing AWD and SUV's.
my E and S are both sedans but are AWD.
my E and S are both sedans but are AWD.
03-04-2009, 04:47 AM
#24
Originally Posted by Lainey,Mar 4 2009, 07:36 AM
does not pertain to tire question. 
). This is an SUV thread.
03-04-2009, 04:48 AM
#25
Originally Posted by Bass,Mar 4 2009, 08:10 AM
i don't own an suv 
but if i did i would crush it if the President asked me to
my Lebaron gets 25 mpg even on sprirted driving (ie any driving with the death wobble )
but if i did i would crush it if the President asked me to my Lebaron gets 25 mpg even on sprirted driving (ie any driving with the death wobble )
03-04-2009, 04:55 AM
#26
Registered User
I remember hearing this going back to the Mitsubishi 3000GT and Eclipse when they had AWD systems in them.
A lot of it depends on the AWD system itself, in how it's designed. AWD itself is a term that is near-meaningless, because there are so many different systems. Some are purely mechanical, like older Audis and Subarus, that rely on a Torsen center diff (Audi) or a viscous coupling center diff (Subaru).
Many newer cars (Even vehicles like the Ridgeline) are primarily FWD, and use a computer controlled clutch pack system to redirect power to the rear when it senses that the fronts are spinning faster than the rears (and hence are losing traction) It's the same concept as ABS brakes - the system monitors wheel speed very accurately... if there's a discrepancy, the wheel moving faster than the others when you're on the gas has less traction... if you're on the brakes, the wheel moving slower has less traction.
So the problem becomes when you change tire sizes - many electronic systems are sensitive enough to tell. 1 fresh tire will have a slightly larger radius, and turn slightly slower than the others. An electronic AWD system might interpret that as a traction issue, and re-direct torque to that wheel. If it did this momentarily, it wouldn't be a problem. But if you drive thousands of miles like that, you're gonna break it.
It's the same reason why you put the donut spare on the FRONT wheel of the S2000, not the back wheel. We have a Torsen (TORque SENsing) rear differential, which will mechanically compensate by sending power to the wheel with more torque (and therefore traction.) If you have different tire radiuses (radii, whatever...) it will constantly compensate and wear out the diff.
The crux of the issue is, of course, how much of a difference is too much? That answer will change based on the type of AWD system, which in itself is not that easy to find out. They don't tend to publish the technical details.
Unfortunately, I don't think anyone knows exactly how much is too much of a tread difference. Yes, the tire shop wants to sell you more tires. But it is the conservative answer.
A lot of it depends on the AWD system itself, in how it's designed. AWD itself is a term that is near-meaningless, because there are so many different systems. Some are purely mechanical, like older Audis and Subarus, that rely on a Torsen center diff (Audi) or a viscous coupling center diff (Subaru).
Many newer cars (Even vehicles like the Ridgeline) are primarily FWD, and use a computer controlled clutch pack system to redirect power to the rear when it senses that the fronts are spinning faster than the rears (and hence are losing traction) It's the same concept as ABS brakes - the system monitors wheel speed very accurately... if there's a discrepancy, the wheel moving faster than the others when you're on the gas has less traction... if you're on the brakes, the wheel moving slower has less traction.
So the problem becomes when you change tire sizes - many electronic systems are sensitive enough to tell. 1 fresh tire will have a slightly larger radius, and turn slightly slower than the others. An electronic AWD system might interpret that as a traction issue, and re-direct torque to that wheel. If it did this momentarily, it wouldn't be a problem. But if you drive thousands of miles like that, you're gonna break it.
It's the same reason why you put the donut spare on the FRONT wheel of the S2000, not the back wheel. We have a Torsen (TORque SENsing) rear differential, which will mechanically compensate by sending power to the wheel with more torque (and therefore traction.) If you have different tire radiuses (radii, whatever...) it will constantly compensate and wear out the diff.
The crux of the issue is, of course, how much of a difference is too much? That answer will change based on the type of AWD system, which in itself is not that easy to find out. They don't tend to publish the technical details.
Unfortunately, I don't think anyone knows exactly how much is too much of a tread difference. Yes, the tire shop wants to sell you more tires. But it is the conservative answer.
03-04-2009, 04:56 AM
#27
Originally Posted by Legal Bill,Mar 4 2009, 08:47 AM
Sorry Ms. Walmart ( ). This is an SUV thread.
). This is an SUV thread.
Back to the tire question. We have had AWD vehicles. The person in charge of vehicle maintenance in our home says if there was just a little wear on the tires, he may only change out two of them. If the tires are more than just a little worn, no question, he would change them all.
03-04-2009, 04:57 AM
#28
On my car, I push a reset button and the electronics sets itself to the current tire conditions.
03-04-2009, 05:04 AM
#29
Registered User
As a follow-up, I have an Audi A4 with Quattro, which has a torsen center diff with a 50/50 front/rear torque split normally. It's got open f & r diffs. It comes with a donut spare... so it must be OK to drive for a little while on it... but despite having checked into it, I've never found a proper answer. I rotate my tires regularly, and fortunately haven't had to replace a tire.
I would at the very least replace 2 at a time. And I'd keep the other half-worn tire rather than throw it out. That way, I have more options if it happens again.
I would at the very least replace 2 at a time. And I'd keep the other half-worn tire rather than throw it out. That way, I have more options if it happens again.
