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Mixing OEM Pilot SS with A/S 3 Plus

 
Old 06-13-2019, 01:33 AM
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lynndm
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Default Mixing OEM Pilot SS with A/S 3 Plus

I'm ready to replace the
fronts on my '14 Z51 with 18K on the clock. They measure 5/32 on LF and 4 on RF, both even wear. Rears measure 6 and 7. The RF precipitates replacement of the fronts and I've decided to go with the Michelin A/S 3. But I hate to lose the wear remaining wear on the rears and wondering if there are any issues with mixing the two tires until the rears are needing replacement also. What do you guys think?

Doug in North Texas

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Old 06-13-2019, 06:54 AM
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Dcasole
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Doug , you do know that brand new the tread depth is only 9/32 right , your tires are not worn out yet ...
Don't mix run flats and non runflat
Dave

Last edited by Steven Bell; 06-13-2019 at 04:07 PM.
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Old 06-13-2019, 07:57 AM
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I know a lot of people on here are going to say never to mix different tires, and not to mix run flats and non run flats, but other than the fact that the handling won't be 100% perfect (if you're tracking the car that is) there is no safety issue here. When I first got my C5 it had run flats on the back and non run flats on the front, and I drove it that way for at least a year until the rears needed replacing. And when they did need replacing I chose a different brand on the back compared to the front, until those fronts wore out and then I bought the same tires. I drove that car for 9 years and added 100,000 miles on the odometer and there were many times when I only bought 2 tires at a time and bought something different compared to the other end of the car. No problems whatsoever with this practice.

When I need tires for my C7, I want to switch to all season run flat Michelins, but I'm not going to replace all 4 at the same time if the rears wear out way before the fronts do (or vice versa). That's just money down the toilet IMO.

For those that are going to say not to mix tires, what exactly do you think is going to happen? It's not like you're going to get a blowout, or the car is going to handle dangerously. Like I said, if you're tracking it, there would be a difference, as the difference in tires would make it either understeer more or oversteer more, but a hard core racer would have dedicated track tires anyhow, so it's not even an issue here.
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Old 06-13-2019, 08:33 AM
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Part man you are certainly entitled to your opinion but there are many posts and threads by all the tire manufacturers and sellers that state the you should never mix runflats with non runflats because of the different tire construction will cause a major imbalance in the handling of the car especially at highway speeds and inclement weather. Also it is not recommended to mix an all weather tire with a Summer only... so now there are 2 strikes , non runflat and all weather tires

I drive my car as an "almost"daily ...I bought the car used and it had brand new Michlen AS 3 non runflats on the front and and older run flats on the back and I can tell you from my experience that there is a huge difference in the handling, i really could feel the back end kick out when i was on a road that had anything less than a smooth pavement . Having to do a quick maneuver on the highway or in the rain might end up with the car heading in a direction that you dont want to be heading ...

It did not take me long to replace all 4 of those tires and I had to try to explain to my wife why I was replacing perfectly good front tires .

Dave

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Old 06-13-2019, 10:21 AM
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I don't see anything where he says non-runflat for the AS/3, which are available in stock sizes in runflat. I just replaced my fronts with runflat AS/3 + in stock sizes due to extreme inner wear (hadn't had the car aligned since I bought it last year). I had about 4-5/32nds on the outside, but the insides were down to the cord on one tire and bald on the other. Rear SSs are fine at 4-5/32nds all the way across. I drive the car daily, and it's fine. These two models of tires are so close in performance that it's not going to be noticeable as far as handling goes. Heck, there's plenty of people who run drag radials on the rear, which is going to be WAY more difference than SS vs AS/3.
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Old 06-13-2019, 10:27 AM
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Originally Posted by Evan70 View Post
I don't see anything where he says non-runflat for the AS/3, which are available in stock sizes in runflat. I just replaced my fronts with runflat AS/3 + in stock sizes due to extreme inner wear (hadn't had the car aligned since I bought it last year). I had about 4-5/32nds on the outside, but the insides were down to the cord on one tire and bald on the other. Rear SSs are fine at 4-5/32nds all the way across. I drive the car daily, and it's fine. These two models of tires are so close in performance that it's not going to be noticeable as far as handling goes. Heck, there's plenty of people who run drag radials on the rear, which is going to be WAY more difference than SS vs AS/3.
That's why I would be confident mixing all season run flat Michelins with the OEM run flats, simply because many people have said they are very close in dry performance.

And I also once ran drag radials on my 98 Formula for about 5000 miles worth of street driving (with the OEM Goodyear GSC tires up front) and it was just fine. At the extreme end, I also had a supercharged 87 Mustang GT that I drag raced a lot and on the street I ran skinnies up front on radials, and out back I had McCreary cheater DOT tires (bias ply!) Obviously the handling on that car went right out the window, but I drove it like that for years and never got into trouble.
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Old 06-13-2019, 10:52 AM
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Personally I call a place like Tire Rack and talk to them Ask the question. If you want to double check the answer you get from TR, go to a local store, like a Goodyear dealer and talk to them, I picked up a nail in a Conti Extreme Sport tire. Wanted to get a replacement and found that my particular tire was not being made, but there was a replacement that pretty much matched the old tire (even had the same name). Was told by two different places that it's always best to replace all 4, but at a minimum run to identical tires on the same axle. Mind you, I was not mixing RF and non-RF's, so cannot speak to that at all.
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Old 06-13-2019, 11:11 AM
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Originally Posted by Dcasole View Post

I drive my car as an "almost"daily ...I bought the car used and it had brand new Michlen AS 3 non runflats on the front and and older run flats on the back and I can tell you from my experience that there is a huge difference in the handling, i really could feel the back end kick out when i was on a road that had anything less than a smooth pavement . Having to do a quick maneuver on the highway or in the rain might end up with the car heading in a direction that you dont want to be heading ...
I see what you're trying to say, but think about it this way. If the rear tires were kicking out on rough pavement, that is independent of whatever tires were on the front. Those rear tires would still kick out even if the tires up front matched them. This just illustrates that the new tires up front now have better grip in the corners, causing you to drive slightly beyond the limits of the rear tires. But if you had the same tires up front as you had out back at that point, you'd be cornering slower overall because now the fronts wouldn't grip as much. See what I'm getting to here?
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Old 06-13-2019, 11:21 AM
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Best to un 4 of the same BUT 2 different at each end will be no safety issue .
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Old 06-13-2019, 11:42 AM
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The HACK
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I look at this dilemma from this perspective.

No manufacturer in the right mind is going to tell you "yeah, it's perfectly fine if you run something that is going to be slightly detrimental to your car's performance and your safety," no matter how SMALL the detriment is. It's just plain stupid in our litigious society.

The REAL truth is, there IS a factor of decreased performance and safety margin by mixing tires. Said factor varies between what you actually do and what product is placed where, and what type of construct there is in the tires. The variations are huge, but the actual decrease in performance and safety margin is actually...well, not CRITICAL. It's not like when you put different tires between the front axle and the rear axle you're going to immediately go Mustang leaving car show.

HOWEVER.

There are some universal truth behind WHY it's recommended not to mix tires front and back, and you must use your best judgement as to why to mix or NOT to mix. The variables involved are:

1: Mixing compounds side to side
2: Drive orientation (FWD, RWD, AWD/4WD)
3: Compound designated use (summer, winter, all season, competition)
4: Intended use

On mixing tires side to side? Don't do it. It is not prudent nor safe to have different compounds between the left and the right. This is just simple physics and basic common sense, different compounds, even different brands within the same performance category, mixing different tires from left and right creates different grip levels and a natural "torque" when forces act upon the chassis. When replacing tires, the rule of thumb is always replace the left and the right tires on the same axle with the same brand, make, and model of tires.

On drive orientation, if you're kosher with not mixing tires side to side, you would always want to put the best gripping tires on the drive axle. That means on a FWD car, you put the best gripping tires on the front, RWD the best tires in the rear. This, of course, is contingent upon the ability to rotate front to back. If you can't do that, and you certainly CAN'T on a Corvette, this whole scenario is moot. You replace whatever axle is worn. But if you CAN rotate tires front to back, you should put the new tires on the drive axle. AWD and 4WD becomes somewhat sticky, as any wheel and axle can be driven, and this becomes trickier because you'd ideally need to put the same compound all around on AWD and 4WD applications, but when you replace a single axle, you should put the new tires in the rear in AWD and 4WD cars (these typically have wheels and tires that can be rotated), and they all should be of the same brand, make, and model. IF you were in OP's situation, where one axle wears out first ,and you need to replace those tires, you would ideally put the better tires on the drive axle. So in this instance, say, the OP wants to move from the better gripping summer PSS tires to slightly less grippy all seasons, you would want to replace the front axles to all seasons first. This means, if the rear tires wore out first, you would replace the rear axles with the same PSS, so the rear axle will have the better (newer) tire, then as the front axle wore out, you'd replace the front tires with all seasons, then when the rear axles wore out, you'd replace the rear tires with all seasons so they'd all match.

Ideally.

However, with modern day stability control systems, there really is very little danger to replacing the REAR tires with a slightly less grippy tire. Unless you go to the extremes of say, putting Cup 2 tires up front, and winter tires in the rear during summer time. Or run all seasons up front, and Hoosier slicks in the rear during the dead of Minnesota winter. These are typically the idiot situations that manufacturers have to consider when they put out the warnings about not mixing tires front and back, because you KNOW someone is going to do it, Mustang leaving cars and coffee their expensive car, and sue the tire manufacturer for the possibility of even mixing tires front and back. So any sane tire manufacturer is going to tell you to NEVER mix, because with that statement, they sort of idiot proof themselves and divest their liability. Again, if you follow the rule above, by putting the better tire on the drive axle (or in AWD and 4WD, better tires in the rear) and by leaving traction control and stability control on, you should be okay as long as you're not going to the extremes of mixing two vastly different compounds designed for vastly different purposes. As long as you keep the tires within 1 standard deviation of this order: Competition > Extreme Summers > Summers > All Seasons > Winter. What I mean by this is, don't mix Extreme Summer tire with All Seasons. UHP summers and all seasons? Probably okay. Summers and Winters? Not okay. Slicks and UHP summers? probably stretching it. Reason being, there's enough of a gap between what each of these tires are designed to do, that under certain situations on the opposite end of the weather spectrum (dry, wet, hot cold...etc) you can come across a situation commonly where the grip levels between axles are large enough that stability systems can't overcome the laws of physics.

There's also the argument about mixing runflats and non-runflats brought up in this thread, and again, my recommendation is, it's not ideal, but if you leave traction and stability control on, it aint' going to...You know, Mustang. But it IS altering the spring rates between each axle and create a natural "torque" on the chassis when the limits of grip is approached or exceeded.

Which comes to the last part, INTENDED USE. I for one track my cars. Regularly. And I drive spiritedly in all the wonderful mountain roads in Southern California because I do live in PARADISE. *I* would NEVER mix tire compounds front and back, unless I'm in a pinch and need to get from point A to point B and have no choice but to mix compounds (it's happened before). In those situations I drive carefully, leave all traction aids on, and at first possible moment remedy the mixed compound. In my case, I almost always either keep the tires the same compound when one axle wears out, or if I change compounds, I change all 4.

But I realize most people don't use their cars like I do.

For the vast majority of your plebeian vehicle use, the situations and rules I stated above works 99% of the time. Again, for that 1%, the manufacturer is going to RECOMMEND not mixing compounds, because it IS detrimental to performance and decreases, ever so slightly, your safety margin. If you intend to carve canyons in sunny and arid Arizona, where it rarely ever rains and it's almost always above triple digits except in the dead of winter? Leave traction control and stability control on, and don't try to go 10/10th through every turn, and just be aware that YOU are the driver, not the passenger and you are fully responsible for your actions, and understand the limits of your skillset? If all these conditions are met, there's absolutely no reason why a set of PSS runflats in the rear and a set of Pilot Sport A/S3 non-runflats in the front is going to stop ANYONE from enjoying themselves. Even if the all seasons are in the rear, as long as you understand that the rears will likely go past the the limit of adhesion first in a corner, but stability control and traction control is likely going to have to work overtime, you should still be relatively safe. Not ideal, but safe. If all you ever do is cruise down a straight boulevard with the top stowed away at 15 mph under the speed limit, never EVER out in the wet and never in the cold or extreme hot? I wouldn't go mixing tires left and right, and Hoosier slicks front and studded winters in the back for sure, but all seasons front and summer tires in the back until you can eventually replace the worn out summers in the rear? Knock yourselves out.

HAVING SAID ALL THAT.

All these rules that manufactures put forth are all RECOMMENDATIONS. They can't stop you from putting studded snow tires* on the rear passenger tire and Cup 2s on the driver's front. And some bubba WILL do that, and live to tell about it. Just like on occasion I will have a beer on date night, and still drive the 5 miles home. Ideally you should NEVER drive even with a single drink, but the law states legal blood alcohol level is 0.08% and it takes 2 drinks within a 1 hour time frame for my body size to reach that limit (actually, my PD buddy gave me a breathalyzer test at one of our parties, and with 2 drinks in a 15 minute span**, I blew a .045.)

* Manufacturers may not be able to stop you from doing this, but some local constables can. Certain municipalities ban the use studded snow tires

** Never, EVER drink and drive. Most of the time, if I have 2 drinks, I'll have the missus drive home. That's why we almost always go date night in the diesel. But my PD buddy also tells me that they always wait 15 minutes when they pull you over because technically it takes that long for your body to absorb the alcohol, so they make you sit for 15 minutes and administer other field sobriety tests before they ask you to blow, otherwise the results will be off.
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Old 06-13-2019, 11:52 AM
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Yep I agree with all of you except I still would not mix a runflat with a non runflat . I think the OP will be fine with replacing the fronts with the AS3 as long as they are runflats so they match his back tires

I had MT drag radials that I would use on track nights on both my C6 and my C7 which both have runflats and it was down right scary at the top end , changed my C7 over to the AS3 non runflats on the front with the MT's and the difference was like night and day car was just as stable as having my stock tires on

Having the AS3 non run flats on the front along with my stock rear MPSS runflat rear tires I felt the same type of instability which feels like the rear end is wiggling around and has nothing to do with the front tires being newer or handling better ......

Dave
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Old 06-13-2019, 01:50 PM
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I say "no" to mixing new and old tires (not so much the type or brand). My reasoning is that once you first do that, you'll be doing it for entire time you own the vehicle. Two new, two old all of the time. But, that's just me.
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Old 06-13-2019, 02:06 PM
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Originally Posted by Rebel Yell View Post
I say "no" to mixing new and old tires (not so much the type or brand). My reasoning is that once you first do that, you'll be doing it for entire time you own the vehicle. Two new, two old all of the time. But, that's just me.
True, that makes sense, but then at the same time you'll also be throwing away a lot of tires long before the end of their useful life, as it's rare on a Corvette (in my experience anyway) that the fronts and the backs wear at exactly the same rate. A lot of times you might find yourself going through almost two sets of rear tires before doing the fronts once. Over the life of the car that will get very expensive if you're replacing tires that aren't near the end of their life yet.
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Old 06-13-2019, 02:32 PM
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Other thing to throw in is age of tires. You should really replace tires every 5 years anyway, and if you don't drive it often you might end up just doing all 4 at once. If it's a daily/frequent driver, then I come down on the side of doing 2 at a time being ok based on wear.
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Old 06-13-2019, 02:55 PM
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Originally Posted by Patman View Post
True, that makes sense, but then at the same time you'll also be throwing away a lot of tires long before the end of their useful life, as it's rare on a Corvette (in my experience anyway) that the fronts and the backs wear at exactly the same rate. A lot of times you might find yourself going through almost two sets of rear tires before doing the fronts once. Over the life of the car that will get very expensive if you're replacing tires that aren't near the end of their life yet.
I didn't have that problem with my C6's as they wore pretty much at the same rate. But, I admit I have no experience with the C7 yet.
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Old 06-13-2019, 03:04 PM
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Thanks for all the input. I was considering non-run flats when I had a quote from my local Discount tire store of nearly $500 difference between run flats and non-rf but found they had made an error. For the $125 difference in price, I think I'll stick with the rf tire and have the convenience of driving in case of a flat. Have done that once so far.
What measurement do you guys think is safe to run on the front with the OEM tir? I occasionally find an open deserted 4 lane and drive 140 - 150 mph and don't want to compromise safety. The dealer may be trying to get me to prematurely replace the fronts with one tire measuring 4/32 and the other 5/32. I generally go further down into the wear bars but not driving this fast on my other cars.

Doug
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Old 06-13-2019, 03:07 PM
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Originally Posted by Rebel Yell View Post
I didn't have that problem with my C6's as they wore pretty much at the same rate. But, I admit I have no experience with the C7 yet.
I don't have enough time with my C7 to say for sure how it's going to wear out it's tires (they all honestly still look like new!) but with my C6 and C5 I had a lot more rear tire wear than front. I'm sure all those full throttle launches from a stoplight had nothing to do with that!
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Old 06-13-2019, 03:37 PM
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If it is a '14 with original tires, those are probably now six years old.
It doesn't matter how much tread they have; they could have been sitting on a shelf since manufacture with zero miles driven. They are timed out. I would definitely replace all four. Chances are the level of grip they were designed to have is seriously compromised at this point, or well on the way there.

I waited about that long to replace the tires on my C6. One eventually got a nail and I replaced all four, and should have a couple years before that. It was WAY too easy to slide that car around with ~6 year old tires.
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Old 06-13-2019, 03:56 PM
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I usually replace mine when they get to the wear bar at any part of the tire. Fronts wear the inner side faster, so you may have 4-5/32nds on the outside, but 2/32nds (wear bar) on the inside. 4-5/32nds is still plenty of tread if the wear is even across the tire, and I wouldn't replace them unless they are over 5 years old.
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Old 06-13-2019, 04:00 PM
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Originally Posted by ny32182 View Post
If it is a '14 with original tires, those are probably now six years old.
It doesn't matter how much tread they have; they could have been sitting on a shelf since manufacture with zero miles driven. They are timed out. I would definitely replace all four. Chances are the level of grip they were designed to have is seriously compromised at this point, or well on the way there.
I drive enough that my tires always wear out before they "time out" but if I ever had a situation where I still had a lot of tread on a set of tires but they were 6 or 7 years old (from the date of manufacture as stated on the tire) I would definitely replace them. That's one area where I strongly believe a tire can be dangerous.
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