ca993twin

Franklin,

I know that's the good, safe, conventional wisdom. I believe the new Lotus Elise is coming with different tires front/rear. There really is no good reason why they need to be identical. Drivers quickly adjust to much bigger dynamic changes without even noticing... a big heavy friend in the passenger seat, a full load of gas, slight differences in tire pressure, tire wear... these produce much bigger changes in the driving behavior than the differences between two different, but similar performing tires. This is not to say that if I were buying four new tires, they wouldn't match. But I wouldn't toss away two good tires because of this conventional wisdom.

Allen

I think common sense says that if you are basically just cruising around the country roads and not pushing the car at all, mixing the tires is not going to cause you any problems. My guess is that everyone who is on the "can't mix tires" side of the fence is refering to performance oriented driving.

Personally, I'm really not sure if mixing is a problem or not when you are performance driving. BUT...if in fact it IS a problem, then it would only take one slip/push/oversteer/understeer to cause a real bad situation.

Personally again...I would get (4) new tires of your choice, and call it part of the price of your new car...kind of like getting the oil changed as soon as you got your new car home......some things you just need to have first hand knowledge of their condition/state....IMHO

mike cap

aap,

You don't mention how many miles on your car, but if the car is low mileage, say 15,000 or less, the tires may be original, since the SO2's were original equipment.

When I bought my car two years ago at 19,000 miles it had the original tires. Hard to believe, but I talked to the PO and it was true. The backs were down to the wear bars and the fronts still had some life. But all four were cupped, weather "checked" and generally looked like crap

If you think you still have originals on the fronts, replace all four, For $500, it's just not worth the risk to be rifding around on 6 year old rubber.

KRA993tt

aap,

If you end up using Tirerack for the tires. Ask for a list of installers in your area then go check them out. You should not have too much trouble finding someone for the job. FWIW I purchased some from them and found out they have a warehouse here in DE so shipping was relatively cheap and quick.

Chris C.

I'm firmly in the "don't mix tires" camp. Guys--you can feel a difference from just 1-2 lbs of tire pressure in this car, it is that sensitive to contact patches and weight transfer. If you have the car, you're gonna drive it. Why risk amplifying things in a potential emergency situation that could cost you the entire car?

I will go with Pilots next. Good enough for the GT3... I have been dissappointed with Pzeros--mine flat spot if the car sits for just an hour.

I do NOT recommend the Kumhos at all! Had em on another car as a replacement for Pilots and the difference was staggering! Normal driving caused the ASC (traction/anti slip control) to activate quite frequently. Cheap, but clearly a compromise.

Just my $0.02 of course.

993Widebody

I really wouldn't mix tires, but that is just me. There was a long thread recently in which I received a lot of heat, just because I didn't believe having front tires that were worn along with new rear tires of the same brand, would cause the car to feel unstable. Apparently I was wrong, because the original poster replaced the front tires and reported the car's unstable swaying went away. This was I believe on a C2S and the car was only being driven on the street in a "normal" fashion.

In terms of brand/tire, I feel for the $$$ the S03 PPs are probably the best max performance street tires out there if you don't want to be replacing the rears every 8k miles or so. I am sure there are probably good cheaper alternatives, as well as possibly slightly better more expensive tires, but everything considered I am happy with their performance given their wear rating. Tire rack is a good way to go.

Greg Fishman

Everyone knows that you are free to choose the tires you want on your own cars. If you want to get them at WalMart or re-treads, that is your perogative. But to advise other people that there is no reason to match up tires on a high performance car is just wrong. Keep that type of advice to yourself. Unfortunately there may be people reading this thread that might actually listen to you. Hopefully their tire shop will bring them to their senses before they make a critical mistake....

Franklin229

Greg/993Widebody/Chris
Thank you-I am amazed at how sensitive these cars are to tire pressure. I am at a point now where I can literally feel a difference through the wheel should one tire be off-pressure wise. I can't imagine having odd tread combinations on the car. Mixing tires is just hack-sorry.

Carrera Mike

aap,

I recommend S-03s, Bridgestone Potenza. I just got mine and very pleased with them.

If you want to read reviews (on any tires), go to tirerack.com, pick a tire and in the bottom right, you'll get a link review where you can narrow it down to Porsche drivers, and narrow it further from mild street drivers to fast and aggressive.

ca993twin

Well, there's that flack I mentioned. Here's the deal... some of us have actually tried mixing tires with pretty good success. Others will always go by the book, and do the safe, conventional thing. I'm sure that way back, when people were suggesting mixing different SIZES of tires, they got the same reaction. But today, even the factory mixes sizes, and we think nothing of changing them even more. With tires of similar performance characteristics, changing sizes will probably produce a more dramatic change in feel and handling than mixing brands. Remember, the original question was asked by a guy who didn't want to toss away two perfectly good tires, and doesn't drive aggressively.

Oh, and I think that Greg's advice that I need to keep my opinions to myself is flat-out wrong.

Stevarino

Greg et al:

I was wondering if you guys could articulate your positions on why mixing tires is not recommended for those of us soon facing that quandary. It would be a great service to the Rennlist community to establish an authoritative thread; outside of mixing tires is "wrong" to just plain "hack", for those of us who made it past the 12th grade.

For example, someone above suggested that the ABS system wouldn't like mixing tires, establishing that person's lack of understanding regarding ABS technology. As for matching wear, given that the rears always wear faster, that can't be the reason. Perhaps there's an engineer in the house.

'Looking forward to more interesting and objective posts. Thanks in advance.

Greg Fishman

Steve,
What does pretty good success mean? That you haven't killed anyone yet? Or that the car rides good?

So what if the original poster doesn't drive aggressively? What if he has to avoid a car or another object or person that is in his path? Should he still not drive aggressively to avoid them because his tires may not work as intended?

Since you seem to promote or at least suggest that this set up is safe and benign, I have a few questions for you. Have you tested your mix/match set of tires in all types of situations? In emergency maneuvers, at high and low speed. In wet and dry conditions? With tires at full thread or with half or a quarter of their life left? If not then I believe I am perfectly in my right to suggest you not preach what you say as gospel. You could, inadvertently be putting yourself and others at grave risk. The factory does this type of testing on a regular basis and I would rather bet my life on their assumptions vs. yours.

Changing sizes (up or down) is not in the same realm as what you suggest. Increase tire width by 10-20mm will not have a dramatic effect on grip characteristics or overall performance. Having a tire that has more or less performance on the back end of the car could have dire effects.

Greg Fishman

I think I answered that in my previous post directed at Steve. There is an element in life we call faith. I have faith in the engineers at Porsche over the few naysayers on rennlist that have done this "with some degree of success" I will never have privy to all of the engineering data that Porsche used, nor would I be able to understand it. But I have faith in their knowledge and expertise and I think it is wrong to suggest otherwise without any empirical evidence to the contrary. If a power line was down in your front yard, would you touch it? Why? Maybe it wouldn't kill you even though it is "common knowledge" that it would.


Porsche does have to cover their asses from litigation but I believe they want our cars to perform as they intended and that means a proper set of tires. Tires as you know are the only things that keep us on the road and I believe they spent more than just an afternoon deciding on what these cars need in that regard. If you want some engineering or statistics then I am the wrong guy for that.

STLPCA

ON
This (tire quality & mixing) is a topic that periodicially comes up. Frankly, I just don't get it. However, I do get (& agree with) Greg's pointed posts. I would guess that many Rennlisters are well above average in car acumen, but others rely heavily on the advice they get here & may (wrongfully) take it as gospel. I disagree with the suggestion that a Porsche driver who doesn't "push" the car should get by with lower performing tires. Tires are the limiting factor for street handling or braking, either of which may determine whether you or your passenger lives or dies in an unexpected emergency situation. Even the most aggressive street driver will likely never intentionally call upon his tires to perform at 10/10ths, the level demanded by a true "panic" stop or by a real emergency evasive maneuver. Why buy a Porsche if, when you least expect to rely upon, but most need its extraordinary brakes or handling you've reduced it to a Camry to save a few bucks?

Our cars were designed for 4 matched tires. Breakaway characteristics, adhesion limits, etc. differ even within the same tire brand & model, but much, much less than across brands or models. I've never heard anyone suggest that mismatched tires F & R will be as predictable at or close to the limit. Which takes us back to that "at the limit" emergency - not the best time to learn about idiosyncratic handling. IMHO, mixing tires is dangerous & suggesting that others do it is irresponsible.

All tires represent compromises and none excel in all areas. Each purchaser needs to decide his own priorities, of which price is certainly one. I just think part of the equation should be the cost to car, occupants & others for a wrong decision & acceptance of the possible consequences.

OFF

ca993twin

Greg,

OK. Fair question... what is pretty good success? I push the turbo and the Cobra pretty hard, the Cobra being an ex open-track car and the Turbo, well, keep in mind that I have a lot of experience racing 911s. I have tried mixing tires in order to get the best compromise of price/performance for my cars. No... I do not just plunk down my money for the most expensive tires I can find, and assume they will perform the best. Nor do I have the time, money or facilities to track test various combinations. I have already stated that if you use a crappy tire at one end, and a good tire at the other end, you will be unpleasantly surprised in a hard manuever.

I have Yoko AVS Sports on the rear in 295x30x18, and SO3s in the front in the way-too-skinny 225x40x18 size. Yes, I have some understeer because the AVS Sports stick like mad, and because the 225s are too narrow. Next time I need tires, I'll use a wider tire on the front... AVS Sports if they're available, because I really like them, or something else, if they're not.

So... go by the book if you want. That's the safe thing to do, and that means a lot to some folks. But I've tried mixing, and it works.

Why is it that you feel its fine to voice your opinion, but that I can't voice mine? Have you tried mixing and it didn't work for you? I will always express my opinion as my opinion. If you don't like it, post a reply. But don't dare tell me not to post.