[sevencyclist]

I have read here about not mixing tire brands for the front and rear since different brand tires provide different traction characteristics. I understand this might be a theoretical concern when the tires are brand new.

However, most here on the forum are reporting differential wear of tires by ratio of 1:2 between front and rear, meaning one set of front tires for every two sets of rear. This implies there are times where front traction is much better than the rear, such as right before replacing the rear set for the first time. And also times where rear traction is superior to the front, right after getting a new set of rear tires. There will always be traction difference between front and rear other than when brand new. If this is the case, then why can't one have different sets of front and rear tires, even if there are different between the brands with their performance?

 

[DriveInHouston]

I will give you my experience. I bought a CPO with Goodyears in the front and Michelin PS4S (non Porsche spec, no N0) in the back. I replaced the Michelins at 11k mi. due to a bolt slashing the left rear in a way that was not repairable. Discount Tire had to find 2 MPS4Ss in short order and I ended up with 2 more non Porsche spec.

Two thousand miles later in heavy rain I experienced hydroplaning (the rear axle became really twitchy and had to correct heavily) in the straight on the freeway. It happened twice that day and once more on a different occasion.

I suspect that the difference in brands between front and rear axle played a role. Non Porsche spec also.

Do you want to repeat this experience?

I am running Michelin PS4S N0 on all four corners now.

 

[GTS18BGTS]

This might interest you seven. Porsche N spec Approval

 

[sevencyclist]

Thanks for sharing. I am trying to see if makes sense to mix by getting ”better reviewed” N spec Michelin on rear earlier while the front still N spec P Zero. Or do I buy the “lower reviewed” tire to match.

 

[jimmuller]

My memory says that more than one or two people here have reported that the PS4S w/N0 rating has better rain performance than the P Zero.

 

[DriveInHouston]

I would not mix.

The Michelin PS4S N0 is a better tire, is better in the rain, it is the tire of choice. If you don't want to toss your front tires, stick with the Pirellis PZero N1. Change all 4 when the time comes. My 2 cents...

 

[MikePhDPE]

Just driving street I have no problem mixing tires...it's not like they're going to last that long anyway. Soon they will all be the same.

 

[Third]

I can believe there may be a handling difference between a car where all four tires are matched and one where its tires are pairwise matched front and back. (By the way, I'm also sure that's the case regardless of the car's manufacturer.) But that said, assuming high quality tires in good condition all around, where the tires are designed for the particular road conditions (eg, dry, wet, snow) to ensure an apples to apples comparison, my bet is the difference in performance with four-matched versus pairwise matched tires is small to immeasurable for all but professional drivers. Practically speaking, the way I would approach driving a car with pairwise matched tires is simply to assume overall performance will be limited to the performance or handling characteristics of the "lesser-rated" pair. The least common denominator if you will. I think you implied that would be the P Zeros. I'll stay out of a discussion on the latter!

 

[Viffermike]

To add to what @jimmuller and @DriveInHouston have said, in addition to the N-spec info: mixing brands is a bad idea because the grooving and siping likely won't align well, much less work together well. That's one of the major characteristics that N-spec improves: hydroplaning resistance.

DIH has verified that the major visual difference between off-the-shelf PS4Ss and N0-spec PS4Ss is that the rain grooves are nearly twice as wide on the N0-spec. What's not verified (and what I suspect may be the case) is that the grooves may also be shifted positionally relative to the N0-spec tires on the other axle, so that they align and shed water in tandem, at speed. Remember that tire sizes are offset on our cars; that means matched sets such as N-spec likely have design tweaks like this that off-the-shelf versions don't -- and can't, since track widths vary from model to model.

 

[InTgr8r]

What's not verified (and what I suspect may be the case) is that the grooves may also be shifted positionally relative to the N0-spec tires on the other axle, so that they align and shed water in tandem, at speed

I agree with the posts re NO spec and keeping front and rear the same.
I have experiences running different front and rear tires (not by choice) and it can really catch you off guard at the worst possible time.

Regarding the alignment of grooves front and rear on NO tires, JMO but that's highly unlikely.
That would assume that the car is traveling in a perfectly straight line which is almost never the case.

 

[Third]

Regarding the alignment of grooves front and rear on NO tires, JMO but that's highly unlikely.
That would assume that the car is traveling in a perfectly straight line which is almost never the case.

I'll just add that since offsets differ from model to model, I agree it's a stretch to think that engineers take groove location in the tire in front or behind into consideration.

 

[DriveInHouston]

Bottom line:

Do you want to risk a $60-$80k car for $200-$300 worth of tires (remaining value of your fronts) by mixing tires?

The answer should be NO!

Two subordinate questions:

a) Do you want a set of rears without losing these $200-$300? Buy PZeros N1

b) Do you want best performance possible? Buy 4 MPS4Ss.

The answer is not necessarily b). Most of us would never bring the PZeros to the limit, but if for some reason you don't like them... then b) it is.

 

[Viffermike]

@InTgr8r @Third Playing devil's advocate here:

• Then why doesn't the standard PS4S have the wider rain grooves if that design difference enhances wet-weather traction at speed so much?
• If wider rain grooves equals less rubber contacting the road (logically this seems to be the case), does that mean N0-spec PS4Ss sacrifice a certain amount of dry and low-speed wet-weather grip to mitigate hydroplaning?
• You guys are likely right about groove alignment, now that I think about this more. That makes me wonder, then: What does the N0-spec PS4S do less well than the standard PS4S? I ask because with tires, there is always something lost when something else is gained. That's the nature of tire design: it's a product designed around compromises.

 

[InTgr8r]

What does the N0-spec PS4S do less well than the standard PS4S? I ask because with tires, there is always something lost when something else is gained

I agree, there's always a trade off.

The only thing I can think of is that the general spec PS4S has to accommodate a wider spectrum of application.
To me that means the spec is compromised somewhat to accommodate this.

Porsche on the other hand does not have the same design constraint.
That lets them tweak the spec more specifically to their needs.

 

[jimmuller]

• Then why doesn't the standard PS4S have the wider rain grooves if that design difference enhances wet-weather traction at speed so much?
• ...That makes me wonder, then: What does the N0-spec PS4S do less well than the standard PS4S?

If I had to guess and if I was a conspiracy theorist (not to be confused with someone who studies conspiracies) I'd say that Michelin may have given the non-N0 PS4S more rubber to generate better dry-road specs. Porsche may then have required better wet-road performance which sacrificed dry-road performance.

 

[DriveInHouston]

Mixing N-Spec Tires
Use only tire types tested by Porsche. Only tires with the same manufacturer and with the same specification code (e.g. “N0”, “N1” …) should be mounted on the vehicle. Tires should be replaced no less than in pairs on one axle at a time. Only tires of the same tire make and type must be used. Since many Porsche vehicles are fitted with different sized tires on their front and rear axles, this requires matching the tire brand, tire name and N-specification front to rear. While the tire manufacturers may also build other tires featuring the same name, size and speed rating as the N-specification tires for non-Porsche applications, these tires may not be branded with the Porsche N-specification because they do not share the same internal construction and/or tread compound ingredients as the N-specification tires.

Replacing N-Spec Tires
If a vehicle was originally delivered with N-specification tires that have been discontinued and are no longer available, it is recommended to replace all four tires to a higher numeric N-specification design appropriate for that vehicle. In case of tire damage such as cuts, punctures, cracks or sidewall bulges that cause a single tire to be replaced for safety reasons, the remaining matching tire on that axle must not exceed 30 percent wear. If the remaining tire has more than 30 percent wear from new, it should also be replaced. This rule applies to all four tires on all wheel drive vehicles. Handling inconsistencies may result if this is not done.

Porsche N-Spec Tires Explained | Porsche Spokane

 

[Third]

Bottom line:

Do you want to risk a $60-$80k car for $200-$300 worth of tires (remaining value of your fronts) by mixing tires?

The answer should be NO!

Two subordinate questions:

a) Do you want a set of rears without losing these $200-$300? Buy PZeros N1

b) Do you want best performance possible? Buy 4 MPS4Ss.

The answer is not necessarily b). Most of us would never bring the PZeros to the limit, but if for some reason you don't like them... then b) it is.

I like the practical advice regarding the PZero situation. That said, in my opinion I don't think it's fair to imply that any good quality tire (or combination of tires) in good condition, properly inflated and designed for the current conditions puts a car at increased risk on its own as compared to any other tire (or combination) that fits the same description. Clearly it's the driver's responsibility to stay within a tire or set of tires safe operating envelope. I don't doubt that some tires are better than others, but I just don't feel that a lesser tire or combination of tires puts the car at risk until the driver attempts to go beyond the tire's(s') capability.

 

[Third]

Porsche N-Spec Tires Explained | Porsche Spokane

Just to underscore my point, I believe Porsche's admonition here is directed to the driver looking for peak performance. I believe he or she who doesn't follow Porsche's advice can simply lower their expectations vis a vis extreme handling and all will be fine. My point is mixing tires by itself doesn't on its own increase the risk of an accident.

 

[DriveInHouston]

Look at my experience at #2. I am not prepared to lose my Cayman due to hydroplaning in conditions my Mustang GT passed in flying colors with PZeros. I live in Houston, I know a thing or two about driving in torrential rain.

 

[Third]

Look at my experience at #2. I am not prepared to lose my Cayman due to hydroplaning in conditions my Mustang GT passed in flying colors with PZeros. I live in Houston, I know a thing or two about driving in torrential rain.

You make my point exactly. You were driving in conditions that went beyond the capability of the setup. Had you been driving slower, corrective action would not have been necessary. Clearly other people on the road at the same time stayed in control. I can't argue that "better" tires or a matched set wouldn't've allowed you to travel safely at higher speeds in the same conditions, but you didn't experience hydroplaning because of your tires alone.

Just to make sure we don't lose sight of my original comment, all I was saying was a pairwise matched setup doesn't translate into doom. Such a setup can be driven safely, if not to the same extreme. That's all.

 

[DriveInHouston]

You make my point exactly. You were driving in conditions that went beyond the capability of the setup. Had you been driving slower, corrective action would not have been necessary. Clearly other people on the road at the same time stayed in control. I can't argue that "better" tires or a matched set wouldn't've allowed you to travel safely at higher speeds in the same conditions, but you didn't experience hydroplaning because of your tires alone.

Just to make sure we don't lose sight of my original comment, all I was saying was a pairwise matched setup doesn't translate into doom. Such a setup can be driven safely, if not to the same extreme. That's all.

Driving 60 mph like any other car on the road in torrential rain in all three circumstances should not be deemed beyond the capability of the tire setup in any car let alone a Porsche.

Unless you agree that mixing tires is the wrong setup.

And this is my point. Mixing tires is the wrong setup and if you do it you are asking for trouble. It reduces significantly the road handling in rain, unexpectedly so, I emphasize.

The Service Advisor at Ray Catena Porsche and the Service Advisor at Porsche of North Houston were appalled that I bought a CPO with mixed tires, it shouldn't have happened in the first place. They also thought that mixing tires was the cause of hydroplaning, although they couldn't describe why.