Facing the importance of the tires on the 911, i would like to try different things, with either my 19's lobster or 20's aftermarket wheels..

I'm thinking of using a differents tire front and rear, so i can get the best traction (rear) while getting the steering response i'm looking for.

Is anybody every tried that ? Any recommendations ?

 

This has been written about for as long as I've been coming to the forums. Do not mix tires, plain and simple. If you aren't getting glue-like traction and crisp steering response then you have other problems, like a bad alignment (camber), bad / worn tires, etc. I've been driving on PS2 tires since they were released to the market many years ago. Glue like grip, fantastic steering response with proper alignment, etc.

 

Ok, but why ?

Any logical explanation ?

 

Sure, read the manual that came with the car, search here and at RennList and you'll get all the technical reasons you could ever ask for. Your front and rear tires already are very different. Fronts are 235 wide and rears are 295. Different characteristics. Now you are asking about changing either front or rear to change things further, which could influence ABS, PSM, etc. One would think that if Porsche, Racers, track guys like me, etc. could gain a benefit from putting say Michelins on Front and Pirellis on Back we'd do so.

 

i really don't see how the car's ABS or PSM could possibly ''know'' the tires are not the same front and rear. We are cheating overall diameters (and THAT could be problematic) when switching to 18's or 20's and everything works fine.

Is the same kind of unwritten rule that also applies on audiophiles, by exemple, saying that a B&W speaker must be matched with Classé amp, otherwise the sound will be ruined ?

 

No, it is written. And with good reasons. As Ron said, if it were advantageous to mix and match, those of us who race or track our cars would have done it long ago. And since Porsche is as involved in racing as any manufacturer ever has been, they would have worked with tire manufacturers to develop tires with those differing characteristics front and rear. Oops. They did.

Honest. This has been discussed so extensively you can find good answers by searching, but I will give you a quick summary from an engineer. ... Hmmm. No I won't. I just estimated it will take a page at least to even begin. I have to settle for a re-statement of the conclusion. Tire and chassis engineeers work together to ensure the dynamics of the tires front and rear exhibit consistent behavior as the car transitions from one mode to another. From straight line to braking to heavy cornering for example. They work their asses off on this subject for high performance cars. Simulators, track tests, top drivers in extended instrumented road use. For serious cars like Porsche, the result is a limited family of spec tires known to work smoothly with the computerized systems as well as the mechanical suspension elements.

You dump all that expertise when you say you'd like a little better tracking in front while raising the ultimate grip at the rear. Or anything at all like that.

Best not to do it and just believe the engineers who sweated blood picking the tires they recommend. I do.

Gary

 

How does ABS / PSM work? It senses grip (or lack) and reacts to bring the car back under control. Things can change dramatically in the cold / wet if using different tires. If you change the grip characteristics from front to rear, you therefore can change how the computer systems of the car works.

I'm one of many that will not mess around with overall diameters of tires, especially on the track where you are at the limit. That's why I stick with RA1s / R888 which have about 25.5 front and 26.3 rear overall diameters. Porsche and others have written about this extensively and I'm just trying to help you here where it sounds like you really need to do your own research.

Again, I'll go back to my basic "common sense" point. If there was an advantage, don't you think the track junkies, professional (and amateur) race teams, etc. would be mixing and matching? Many race teams have unlimited budgets to win. Do you think the factory would warn you not to mix different tires?

As I suggested, try searching for this information to get the "technical" answer. Different tread patterns will act differently, especially in the wet. You could think your new mixed set up feels "good" in the dry, and then in the wet you have a totally different animal.

I just spent 30 seconds checking "google" and found:
http://www.tirerack.com/tires/tirete...jsp?techid=136
http://www.dunloptires.com/care/mixing.html
http://www.michelinman.ca/care/tire_...s.html#quest06

 

Thank you Gary for the input.


tire manufacturers to develop tires with those differing characteristics front and rear. Oops. They did.

Yes, what should we think of the Pirelli's Corsa system; Direzionale tires for the front and P Zero Corsa Asimmetrico for rear ?

 

They were designed and tested to work together. I doubt there's any trusted source that has mixed and matched different brands, construction types, tread patterns, compounds, etc.

 

Thanks for the links, but after reading all of them i'm still not convinced. They are talking about not mixing winter and summer tires, not mixing different tires sizes/type on same axle (!) and not playing with different diameters, especially on AWD. Which i all agree..

But let's say i'm thinking about using Yoko Advan AD08 245-35-19 for front and Potenza RE11 305-30-19 for rear (AD08 doesnt exist in that size) i can hardly imagine that my car's overall feeling will be worst than my actual set-up with Hankook v12 on all corners.. am i wrong ?

On my 911 '78 i had once Dunlop Direzza on the front and BF KDW2 on rear and that was one of the best tires experiences i had. But, of course, i do understand that my 997 is a very different car!

 

Since we discuss about tires, here is my latest experience and comments regarding that:

https://www.6speedonline.com/forums/...k-tires-3.html


I tried to save money (Hankook) and now i kind of regret it..
That's why i started this thread...

I'm also curious to know what is the air pression F/R you are mostly using (depending of tire's sizes, outside temp, track or road, etc.. ) ?

 

if you want the best just get the PS2s
ive had bridgestone, contis, pirrelis, faulken and nitto - my ps2s were by far the best

when my new pirellis fade in the back (2 sets of backs to 1 set of fronts) i would consider swapping the backs for ps2s and wait for the fronts to fade. I wonder how bad that is...Porsche service centers typically will not plug/patch tires and they wont mix them for you either

 

2 (or 3) practical advices.
Do not try to 'save money' ever. Instead establish a budget, like for any project. Look carefully at your cash flow and figure out how much you can set aside on your toy on monthly and quarterly basis and operate based on that. It help big deal to set your priorities correctly.

I had estimated first set of mods budget to $10K and subsequent $10K annual and I am keeping to it, if not I would already wasted way too much on useless stuff like carbon interiors, wings, carbon lips, etc. Budget helps to keep everything under control. So if budget allows hankooks only - stick to it.

From my opinion if your car came with stock 19" - put PS2 tires on them and make it your primary street set. PS2 tires are good for street.

For racing get 18" set of wide rims 9" fromt and 12" rear and get discussed above Toyo`s on em - it will allow to drive on them to the track.

For winter you need 3rd set of stock 18" rims with PA2 tires - for those you need to shop on Ebay or look on forums for good set of take-offs you could get really cheap - around of $1K or so - all that relevant if you ever plan to drive during winter.

 

Tires are designed to work with each other, whether they are the System Corsa or MPS2 or any other tire. You can mix and match if you really want to, but you will be in the minority. From the sounds of it you want to do this because you are either unsure of which tire is right for you, if so then this won't tell you what works and what doesn't work as it is not a true test. Or you are trying to change the dynamics of the cars handling with different rubber. If this is the case, I think an alignmnet shop car give you better results, and I doubt that one person will be able to improve these dynamics with tires, when all the engineers have deisgned it to drive a certain way.

 

Stick with dedicated front/rears and don't look back.