I run the same pressure in all 4, about 36psi. I still get the center wearing before the outer edges. Seems to be the nature of the beast with wide tires.

My VW dealer does $50 oil changes, and rotates for free. I do notice the rears wear faster. and they don't last as long as the manufacturer describes. I'll bet I don't get 20,000 out of a set of tires.

 

What size tires are you running?

 

About 10% of my miles are on winding roads and front tires will show more wear before 5K rotation. I run same pressure front and back unless I am hauling something heavy. I assume VW recommends the higher pressure in the rear because of liability concerns associated with rear tire failure with the vehicle fully loaded. I would leave the most worn tires on the rear for the next rotation cycle.

 

I'm running 255/55/18 Firestone Destination ST.
They did put a 19 inch rim on some tregs. they ran 275/55/19.

 

Hi, get a load of this. Had a service writer measure my tyres a while back, original set when I bought the Touareg, and the RH rear was worn more than the rest!

I further inquired with the service manager and he said that is what they have been finding. I have yet to discover the mechanical reason for this. Is due to this vehicle design, road crown, other?

On the wife's ML350 Bluetec, they have two pressures for the rear tyres; 35 normal, 40 loaded. Likewise, I run @35psi on all 4 unless I'm towing, etc.

Unfortunately, I have found once you notice the centre of the tyre is wearing more than the rest of the tread, it is too late. I have never been able to get even wear again by reducing tyre pressure, even by a lot.

 

Yeah - it seems insane to me that people run 46 PSI at the rears on this vehicle with just a driver.

I'm guessing this is why my centers are worn more than the edges in the back. I think I'm going to drop the rears down to 38 and run that at all 4 corners. Really - the back should be lower than the front when it's just a light load, but weight distribution is close enough that running the same PSI is about as good as anyone will get.

 

Also, speed and speed combined with overinflation can contribute to increased wear of the centre of a wide tyre.

So, lower the tyre pressure and slow the heck down!!

Well at least adjust the tyre pressure!! Lol

 

Touareg tires normally wear evenly without any rotation.

The reason the rear tires have a higher pressure than the front is so that the car will understeer in extremis.

It's nothing to do with your supposition about second guessing how people might use the car!

Very few drivers can catch sudden oversteer before the car swaps ends, so the safest bet for car makers is for their car to plow/plough straight on - understeer.

The speed scrubs off and, hopefully, the turned wheels will eventually grip before a big "off" into the scenery or another vehicle.

VW and their tire suppliers have spent a long time, a lot of money and driven many miles to get an optimal balance of ride, handling, grip, tire wear and fuel economy for the car therefore, although there'll be plenty of people suggesting otherwise with their pet theories , the pressures VW list [light load/loaded] are the ones you should be running with.

There is a suggestion in the hand book of raising all four tire pressures by, I think 3, maybe 5, PSI for better economy.

 

I'm not following. Increasing tire pressure beyond what the axle weight needs creates, at least in the rear, an oversteer situation, not understeer. If you want to make the car understeer, you reduce tire pressure to increase the contact patch, and increase mechanical grip. This is why people reduce tire pressure when they're at an autocross (more grip). Most manufactures use torsion bars to change under/over steer, and setup the suspension accordingly. And, you can also change the way power is applied. The 50/50 native split on the treg adds to understeer a lot, just as it does in most Audi's. That's why most performance oriented AWD cars (including the cayenne) have a rear-biased AWD system. This helps the rear rotate a bit when you exit the corner, instead of pushing with a 50/50 split.

It makes sense to me that VW forced an abnormally high air pressure in the rear to combat the thousands of soccer moms and unsuspecting dads that would fill the interior, and then slap on a 7 thousand pound trailer, and not think to check tire pressures. Tires are an owner expense anyway, so it's safer to have cars with a bit more center wear than cars blowing out tires because they're doing 85 mph on a 100 degree day pulling a heavy trailer, or have a loaded car and hit a big bump in the road causing enough loading in the back to trigger a blowout.

Just about ever german car has a range of rear tire pressures depending on load. Even my S4 showed a higher tire pressure up front when empty (nose heavy car), but a higher pressure in the rear when it's fully loaded. I really cannot believe the treg only states one giant pressure in the rear given the huge amount of weight it can carry.

 

Oversteer and understeer are quite simple, look at the diagram.

VW engineered the Touareg to have moderate oversteer. Safety, handling and fuel economy were factors in engineering the Touareg and tire pressure is an important factor. .

 

Nooby said they raise the rear tire pressure beyond what the weight requirements are to INCREASE understeer. And you're saying VW designed the car to have moderate oversteer. Did you mean to say they dialed in moderate understeer? I've never heard of an SUV having oversteer designed into the chassis.

I've never heard anyone say the treg has moderate oversteer. There is more weight int he front, and yet the smaller torsion bar is in the rear. This all points to inherent understeer.

I am still not following how increasing the rear tire pressure promotes understeer.

 

Nooby said they raise the rear tire pressure beyond what the weight requirements are to INCREASE understeer. And you're saying VW designed the car to have moderate oversteer. Did you mean to say they dialed in moderate understeer? I've never heard of an SUV having oversteer designed into the chassis. I've never heard anyone say the treg has moderate oversteer. There is more weight int he front, and yet the smaller torsion bar is in the rear. This all points to inherent understeer. I am still not following how increasing the rear tire pressure promotes understeer.

I meant to correct Nooby's explanation. The Touareg is designed to have a slight throttle induced OVERSTEER. It's what I'd expect from a performance SUV.

Try to give your Touareg throttle coming out of a hairpin curve. You'll notice a slight oversteer. Or try it (in a controlled situation) on wet or snow covered road, it will exaggerate the effect. I'm not saying an uncontrollable oversteer but a slight oversteer. It is safer to have a slight oversteer than understeer in this situation and is what you would expect in a vehicle of this caliber.
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I keep to the recommended 39 psi in front and 46 rear and don't have an issue with uneven tire wear.

I also tow my boat about twice a month and it would be a hassle to inflate the rear tires every time I towed. Plus the TPMS warning would be on all the time if I lowered the rear tires psi.
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How can towing a trailer with gear in the cabin at 46 psi, also be the correct tire pressure when you're not towing? It's either the correct pressure for a loaded car but too high for an empty car, or it's perfect for an empty car, but not enough for a loaded car. This is why most cars that can carry a good load provide a chart of tire pressures based on weight

The touareg has understeer designed into it; not oversteer. This is why the cayenne has beefier sways and a rear biased power delivery - to try and combat some of that push in the corners. Even on the 955 cayenne, you gotta really work at it to get the back to come around.

This tire pressure chart is for a phaeton W12 which is nose have by 6% I think. Notice the empty or light tire pressure chart shows a front tire pressure higher than the back, but for a loaded car, it's higher in the back. The treg is no different than any other car, and the tire pressures in the back don't make any sense unless you're fully loaded. Otherwise, I'd think the tire pressure should be 1-2 psi more up front for a car with just one person in it. If you rotate your tires regularly, you'd probably never notice the added wear with a high pressure in the rear. But, it does't negate the fact that the rear pressure is not necessary for a car with one or two people in it.

 

The touareg has understeer designed into it; not oversteer.

You've mentioned this a few times in this thread..I've owned 5 Touaregs and ALL of them have throttle on oversteer, not understeer.

There is no push in the corners that I've ever felt, the rear always kicks out slightly - exactly how its supposed to.

The only way you feel understeer in these things is throttle off, turn the wheel in ultra slick conditions (ie: snow). apply throttle and it quickly turns to oversteer.

As for tire wear, all the touaregs I've had wore tires evenly. If they don't then you have alignment or stepper motor issues.

 

I understand where you're coming from. My Ford Truck had a different psi for higher loads and I'm not sure why VW doesn't. I tried lowering the pressure but I found the ride to be as good with the recommended PSI.

I do know that the Cayenne, Q5, X5 and ML350/500 all have a rear PSI that is higher than the front with or without load. All have more weight in the front but all have more pressure in their rear tires. Performance SUV's are designed to have a slight oversteer.
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Just to be perfectly clear, the Touareg, like most cars, is designed to understeer when people get into trouble and jam the brakes on or swerve, and the higher pressures in the rear, aided by the electronics, help to achieve this and, hopefully, prevent the car swapping ends due to sudden oversteer which, as I said before, the vast majority of drivers can't cope with whereas most can't go too wrong with understeer.

 

Just to be perfectly clear, the Touareg is designed to understeer when people get into trouble and jam the brakes on or swerve, and the higher pressures in the rear, aided by the electronics, help to achieve this and prevent the car swapping ends due to sudden oversteer which, as I said before, the vast majority of drivers can't cope with.

How would running a higher pressure in the back help it understeer? I mean, I hear you saying it, but mechanically, it doesn't add up. If the car has the same size tires, more weight in the front, yet 6 psi in the rear, then how in the world would running 46 psi in the back help it understeer?

 

That's not a performance feature - pretty sure it was mandated back in 2007 that all SUV's state and use the max load tire pressure. I just figured the T1 would have listed a range since it was made prior to that. The 955 cayenne lists a partial and full load range. With 330 lbs in the car, the Cayenne S lists 37/42 for tire pressures, and 37/46 for a full load.

I've never heard of anyone purposely over filling a tire to attain max performance. Track junkies will take a pyrometer and measure the temp of their tires and adjust as necessary to get as close to an even spread as possible. If VW wanted the touareg to have a bit of oversteer, they would have stuck a larger sway bar on the back instead of that tinny one they use. All the reviews on this car also show that it understeers, and that's with ESP off. ESP is designed to make the car understeer.

 

I have different pressures for part and full load on my 2003 tire pressure sticker by the way.

Oh, and I have a Porsche anti-roll bar on the rear after my original snapped but you'd be hard put to tell any difference from the old snapped bar to the stiffer Porker version! [And I don't hang about either!]

 

All three Tregs I've had have always had even tire wear, though I do rotate them, none has been significantly worn more than the other. I've follow the pressures in the door jam +1 psi.

 

This is my understanding of what actually encourages understeer.

A tire with a lower pressure has a higher slip angle as in the tire wall has more flex and will therefore roll over more when cornering. Engine weight will help this characteristic.

A tire with a higher pressure has a lower slip angle because the wall is more rigid and will therefore roll over less when cornering. Less weight in the rear will result in less tire roll over too.

So, if the higher slip angle [lower pressure/more weight] is at the front wheels, the car will tend to understeer which, as I've said, is the safer option for most drivers.

 

That's part of it (positive camber), but you control that with suspension, not tire pressure. Running the tires too low and you distort the sidewall. Run the tires too high and you lose contact patch. Autocrossers will run lower pressures, but their speeds aren't super high. This is why if you go to a faster track, you take a pyrometer to your tires and dial the tire pressure to as close to even temp as you can across the tread (within alignment specs). If you have an oversteer or understeer issue, you fix that with sway bars or suspension settings - not tire pressure. Nobody specs their car with inherent oversteer, either. VW wouldn't require a higher pressure to fix something they could do from the factory with a slightly smaller rear sway bar (or bigger front). They designed the car to understeer, but even if they'd didn't, it would be damn hard to get it to truly oversteer with a 50/50 power split and no rear torque vectoring.

I think we might be talking about understeer and oversteer in different contexts. The touareg doesn't oversteer - at least by most people's standards (you fellas are the only people I've ever heard say that the touareg oversteers). When you power on out of an apex, it pushes. When you turn in during neutral throttle (not braking but not accelerating), it pushes. Sure, you can do something like lift-off oversteer, or get on the gas in the snow, but that's not really the same thing as saying "this car oversteers." VW didn't build oversteer into this car. No manufacture builds oversteer into a car. Even the M3's and 911's will understeer just a touch, or be damn close to neutral, from the factory. Sure, it's easy to tap the gas and *get* them to oversteer, but inducing oversteer isn't the same as just oversteering.

Read any review on the cayenne. They all report marginal understeer. If the cayenne understeers with better suspension tuning, thicker sways, and a 40/60 torque split (and a ton of HP) - then there is no way the touareg oversteers. And if you read some of the reviews on the treg - that's what they report: understeer. With the V10? Lots of understeer.

Nooby - you basically confirmed what I was thinking if your 03 listed two pressures. I suspect as part of the massive towing capability, the touareg is rear biased in regards to PSI so there is no confusion on what to put in the tires. (not as easy to estimate trailer wight like you would number of bodies in the car). And it looks like they finally just went to spec'ing only the max pressure. Obviously, if you rotate on schedule it seems people aren't having uneven wear problems. I'd bet my box of girl scout cookies sitting here that if the touareg was spec'd to NOT tow anything, the tire pressures would be the same all the way around - like the are on the Q5.

Here is a link to the car and driver site for the Cayenne Turbo review. They list minimal understeer (close to neutral handling). If someone can rectify how the cayenne is close to neutral (but marginal understeer), but the touareg oversteers - I'll eat a pile of toenails. There are tons of reviews on the cayenne from car-oriented reviews, and NONE of them claim that the cayenne oversteers.

You can get the back end to wiggle if you snap into a corner fast, or maybe even step out a tad, but at the end of the grip envelope, the front end will push before the back end comes completely around. That wiggle in a fast corner isn't oversteer - it's 5500 lbs of mass moving around on sways that are too small and tires that are way too small.

http://media.caranddriver.com/files/porsche-cayenne-turbo.pdf

 

I don't know what is "designed into" the treg... But it oversteers. Understeer only happens in snow. In understeer situation (snow/ice) add weight to right foot and you're straight again.

And I know understeer as my other car is GTI and oversteer as I drive a crown vic five days a week.

 

Nick and the Fuzz, I'm glad you guys chimed in. Like I said earlier in this thread, "The Touareg is designed to have a slight throttle induced OVERSTEER...Try to give your Touareg throttle coming out of a hairpin curve. You'll notice a slight oversteer. Or try it (in a controlled situation) on wet or snow covered road, it will exaggerate the effect. I'm not saying an uncontrollable oversteer but a slight oversteer."

Of course if you take your foot off the accelerator or brake in a turn, you will experience understeer. All vehicles do.

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Holly cow! How complicated!
Maintain manufacturer-recommended tire pressure or, (also) recommended by manufacturer for better gas mileage, 3PSI above door sticker air pressure and tires should be wearing evenly on all four corners! If they don't, than check your wheel alignment to be sure angles are within spec. That's it, no freaking complexity about it!

 

It's not that simple, though. A bad alignment won't cause center tire wear, it'll cause inner or outer tire wear. Or if you're lucky, the whole tire will wear evenly if you've got a really screwed up alignment but perfect tire pressures. Think about it - how do you orient a tire on the road so that only the center wears compared to the edges? Answer: too much air pressure. The fact that so many people report center tire wear tells me that lots of people are running more air than they need. I don't blame VW for only spec'ing max tire pressure, but that doesn't mean it's somehow the perfect pressure for every situation.

Here is an 09 M3 review from car and driver, and on their test sheet, they show it understeers marginally. They don't even have a category to report oversteer because nobody designs a car to oversteer. You can GET anything to oversteer, but every car inherently understeers a tad.

http://media.caranddriver.com/files/2008-bmw-m30709-bmwm3-08-ss.pdf

 

My rears wear down a lot faster. A bit higher psi will help, I agree with that. This thing eats through tires like crazy.

 

I understand you're adamant about this steer issue. I don't think I or anyone else will change your mind, but just think about these things:
The scale you reference doesn't even allow for oversteer to be considered. It seems strange considering we all know cars do it, from beaters to top-o-the line cars so it's not a factor? I know AMA riders slide rear tires and bet others do as well to maximize times on tight turns and worn rubber (BC let's face it the tires front/back are only new until they're mounted and lowered to ground).
disclaimer: I personally like car and driver. But c&d are humans reviewing cars on their own scale. Don't forget that. And what type of people are we to take every word they say as gospel. I had a buddy I rode with for two summers me on SV650 him buell lghtn 900+cc. He could only best me in the straights and why? Because he was always reading how to become a better rider and not RIDING to become one! I'm just saying that at 30k miles in the treg I can't help but believe what I've FELT and not what you've read. I do not say this in any negative way, I respect and am open to your knowledge.
As far as tire wear, I only know what my common sense tells me. Which is trust VW until they wear uneven, then come consult the experts at clubtreg

 

Oh I'm not saying oversteer is bad. Trail braking on a bike has it's purposes, just as oversteer on a car does. But, trail braking is a technique that's not inherent in the bike design. And, it's damn hard to do on a street bike. You can get any RWD car to oversteer if you're close to the traction limits and you give it some gas. It's really hard to do on a FWD car for obvious reasons. AWD cars are notorious understeering cars, even the venerable RS Audi's have always been understeering cars. Hit the apex, give it the beans, and watch it push wide. My old S4 could easily power slide with 4 wheels spinning thanks to a massive 450 lbs of torque, but hit an apex on the track and it's understeer. It took a serious flick of the wrist to get the back end to come around, and then a whole bunch of power to keep it sliding. You could only do so much with the sway bars and spring rates, but ultimately people would swap out the torsen diffs for a quaife or they'd modify the diff to a 25/75 power split. The R8 has a huge power split just for this reason.

I'm not sure what you guys are feeling that makes you think this car's tendency is oversteer. But, coming out of a corner at the edge of the grip envelope and then going WOT, and you're plowing head first into the ditch with the ESP off. Hip wiggles, back end stepping out a tad, and little things like that aren't oversteer. All heavy cars will do that, but they settle back inline. Giving it the scandanavian flick might do it, but again, that's inducing oversteer - not the same thing as inherent oversteer. It's fun as hell to slide the back end around in the snow or rain, and it's pretty easy to do in this car when traction is low, but it's easy to do in any car with low traction.

 

I'm not sure what you guys are feeling that makes you think this car's tendency is oversteer. But, coming out of a corner at the edge of the grip envelope and then going WOT, and you're plowing head first into the ditch with the ESP off.

Umm...no. The back end moves out slightly and the front end tracks where you're aiming it. You may be sliding both ends but that's not relevant.

Maybe your touareg needs alignment or suspension work. Everything you are describing has nothing in common with my experience driving Touaregs over the past decade.