Tire life

[aboyandhisdog]

I would like your opinions on tires which are the best for longevity. I get that a rear engine performance car is going to be hard on tires, but I have to believe that it is because of the compounds they use to make all-season tires for performance cars and not the weight of the engine over the rear wheels. Heck, every car has an engine over wheels, yet tires last much better for other cars.

I will never track this car, I don't even drive it hard or corner too hard, I don't drive near the limits in any respect. I just drive like a sane person and mostly the speed limits. I became a 911 loyalist long ago and still love the way the car drives, but I don't push hard anymore. Maybe I have gained a bit of wisdom over the years!

Anyway, I'm tired of getting only 20-25k miles on the rears while the fronts will deliver easily 40-50k miles. So my question...is anybody in Pokes world getting better mileage out of the rears than a mere 25k, and if so, what brand and model tire and are they all-season or summer tires or what?

I am currently running the Conti Extreme Contact DWS Plus all-season tires. I have about 25k on them and the rears are to the wear bars. BTW, I have the alignment shop (Porsche dealer) set them up with neutral camber so that weight is distributed evenly across the tires and they are indeed wearing evenly across the tires.

Thank you for your opinions on this! Need to buy new tires within a week or two.

[blueline]

Hi Tom,

Firstly, say hi to your doggie for me. Hope she's well!

Tires - my experiences are probably not what you'll want to hear but what you're describing is pretty much the norm for me for performance-type vehicles, and that includes a number of Corvettes in addition to the Porsches.

Even Porsche SUV's such as our Cayenne Turbos (the current one and a previous 2014 model) are tough on tires. On the 2014, I had good results with the same Continentals that you are using, the Extreme Contact DWS Plus all-season tires.

However, on the 2019 Cayenne, the OEM Pirelli P Zero Max Perf Summer Porsche "N0" were horrid. They were done at 10k miles. That's my wife's daily and she drives the vehicle like a lamb. No performance driving from her. Zero. (The only time the SUV gets past "Normal" mode and pushed a little is when I'm in it.)

When I replaced the P Zero's I went with what I trust - the Michelin Pilot Sport 4S Max Performance Summer "N0" tires and they've been far superior so far. To be fair, I also got a second set of wheels (21") and tires (Mich Pilot Alpin 5 SUV "N0" winters) and I'll put them on each Fall, so tire wear is spread between two sets.

As for the sports cars, I'd be surprised to get half of what you're getting now on your rear tires, especially with soft ultra hi-perf tires such as PSC2's or even the toned down MPS4S tires. Getting 40 to 50k on the fronts as you are now is awesome in my opinion.

I have Goodyear Eagle F1 SuperSport Max Performance Summer "NAO" (German manufactured) on the TTS (OEM) and they are wearing fine so far but I bet they'll be done at 10k to 12k, if they even make it that far. (Again, I also have winter wheel/tire sets for the 911, so annual wear is shared with the summers.)

Getting too far out of recommended will result in some level of lessened performance. Not sure if significant in your situation nor if any risks safety-wise in case of sudden maneuvers, but that's something to consider.

Hopefully others here with more experience and more miles will have a better reply and better suggestions. If not, the Conti's may be your best all around bet.

[aboyandhisdog]

Holly is well and says "right back atcha"!

I really appreciate this input and it sounds like another set of the Contis will have to be installed unless somebody here has another option for me. Part of me hopes that somebody would chime in with a tire that gets at least somewhere near the term of the warranty, but I guess it is not to be. We'll see...

I just don't see why, say, on my Passat I can expect to get some 50-60k out of a set of tires even with the engine/transaxle sitting right over the steering wheels, while on the 911 the rears (which are only always going straight ahead), I'm lucky to see half that. Why Michelin or any tire mfg. thinks they can only make a long-lasting tire for a "non-performance" car is lost on me. I drive both of these cars the same and if I could get the same tire of the Passat in the 911 size, I bet it would last just as well. I mean, any vehicle can exceed the tire's limits so why don't they give us more options based on how we drive and use the vehicle? I guess I know the answer to that question - $$$$$$$!

[blueline]

I get that thought and there may be a decent compromise, but considering the way true sports cars are engineered and set up, I kind of doubt it, especially for newer models. Then again, there may be something out there, I just don't know what tire it might be for your car.

Manufacturers of these exotic and higher-end cars along with the tire manufacturers spend a ton of money to have specific tires made just for their cars, hence the "N" designations for Porsche. (Or MO for Mercedes, B for Bentley, MC for McLaren, F for Ferarri, etc., etc.)

(Here's a guide from Tire Rack on manufacturer designations: https://www.tirerack.com/upgrade-garage ... signations)

I will add that that the tire design and engineering process is quite specific regarding compounds, tread, carcass design, belts, etc. This is critical in racing but also crucially important for road vehicles. Tires are one of the most important components of driving, performance and safety. That little contact patch touching the pavement is the only thing between the car and the road. Tires are the last piece of the picture (and arguably the most important one) that make going and stopping possible and keeping you going where intended. Understanding that dynamic and how it works is key. Unfortunately, way too many road-going vehicles are out there with totally unsafe tires to go along with the legions of horrible drivers, especially in the U.S.

Sorry - back to the subject! Another thought, as long as you stick to the exact same tire and tire model, changing in pairs per axle is fine. (As well as singly per axle if necessary due to a road hazard failure in one tire assuming the other tire is still at 75% or so.) You could consider changing per axle as needed and be fine I think as long as the same tires all around and as long as you're not going past the wear indicators. That would help a lot as a way to wisely stretch a tire budget. If you're not on track and not driving aggressively, there is probably no pressing need to throw away the still good front tires in your case.

[aboyandhisdog]

Oh yea...no way I'm replacing the fronts yet. They are still at 8/32", which is only 1/4 way through their life (with 25k miles). I just need rears and would try any brand. I have no problem mixing brands axle to axle. I should stick with all season on all corners however, I think.

Amazing to me though that it looks like I am on the way to 50 k (at least) on the fronts, but can only manage 25k on the rears which don't even turn! This just seems odd to me.

[blueline]

Oh yea...no way I'm replacing the fronts yet. They are still at 8/32", which is only 1/4 way through their life (with 25k miles). I just need rears and would try any brand. I have no problem mixing brands axle to axle. I should stick with all season on all corners however, I think.

Amazing to me though that it looks like I am on the way to 50 k (at least) on the fronts, but can only manage 25k on the rears which don't even turn! This just seems odd to me.

Not turning is part of the problem - the rears have to follow the path set by the fronts and the rears don't turn at all, at least not in cars without rear wheel steering. If you never made a turn but drove in a completely straight line forever, you'd get more wear out of the rears.

Also, with 911's there is extra weight and heat adding to increased wear. Unfortunately, there are no full four-wheel rotations as there were in ancient automotive days when most tires were identical in all four corners.

Personally, on any kind of performance vehicle I am not mixing brands ever and most definitely not mixing the type of tire either.

[aboyandhisdog]

Every car I've ever had (front engine) the front tires have worn quicker than the rears. I always assumed it was because the front wheels scrubbed every time the car turned. You're saying it isn't the turning but rather the weight. Interesting...I learned something today!

On a related note...do you know if the toe can be adjusted on the rears? I plan to take the car in for alignment, but the right rear is wearing faster than the left and this has me scratching my head! edit: nothing is bent and the shocks are new.

[blueline]

Many factors affect tire wear and turning is most definitely one of those factors, increasingly so if driving nearer to the turn-in limit (which you're not doing). But you are still correct saying that turns scrub the fronts and cause wear.

The rears also get scrubbed, more so in a turn. And yes, weight and heat can further tire degradation too. There are many factors that go into tire wear depending on the car, how it's setup, how it's driven, the load, the ambient temps, the speeds, the road surface, tire size, etc.

Also, I don't know your tire size but they are probably along the lines of 205's in the front and 255's in the rear. Larger performance tires such as those found on sports cars means more grip which leads to faster wear.

Your car is an incredibly well-engineered machine built to take advantage of those attributes and many others. That kind of performance, even if the car is not driven hard, will equate into faster tire wear - it's the trade off for a car that goes precisely where you want it to.

Regarding rear toe, I don't know about the alignment parameters of your 997 but a Porsche dealer or a qualified alignment shop will. It would be worth a visit to a good tire/alignment shop to get the answers you seek. Explain to them what you're experiencing and see how they answer. Hopefully you'll get straight answers if they know their stuff.

By the way, how long has it been since your 997 was aligned? Was it a shop that knows Porsches, specifically 997's?

I did find the following via a quick internet search: "If you're serious about how your 996/997 handles, you should upgrade the rear suspension with adjustable control arm links. There are two major drawbacks to the factory links: 1) You can't lower your car and maintain proper suspension geometry. The factory links create too much toe-in, which cannot be adjusted out, creating handling problems and excessive tire wear. 2) The factory links have rubber bushings, which make handling imprecise, especially in performance driving when suspension loads are highest."

There are several really good aftermarket suppliers of suspension upgrades if you ever decide to go that route.

[aboyandhisdog]

Very good stuff, Tim! I plan to go to a Porsche indy this week to see what they know, and will ask about the rear suspension. The adjustable control arms sound intriguing!

My rears are 265-40-18. I had a Porsche dealer do the alignment last about 3 years ago. I plan to go to a specialty shop this time around (Poudre Sports Car). They seem more up to speed with the cars than the dealer as best I can tell - especially where mods are concerned.

Thank you!

[blueline]

You're most welcome Tom - glad to help as best I can.

I realize that whatever direction you go, ascertaining whether or not it helped will take time. However, even if 6-months or more down the road, it would be great to hear what you did and if there was any improvement in tire wear and/or handling.

Also, I'll be curious what you find out about the current alignment, whether it is or is not set correctly. An alignment machine is only as good as the technician doing the job!